intel: Use the correct size when allocating reloc_target_info array

Thomas tracked down this error with kdm and commit b5096402:

==4320== Invalid write of size 8
==4320==    at 0x9A97998: do_bo_emit_reloc (in /usr/lib/libdrm_intel.so.1.0.0)
==4320==    by 0x9A97B9C: drm_intel_gem_bo_emit_reloc (in /usr/lib/libdrm_intel.so.1.0.0)
==4320==    by 0xAED3234: intel_batchbuffer_emit_reloc (in /usr/lib/xorg/modules/dri/i965_dri.so)
==4320==    by 0xAF13827: brw_emit_vertices (in /usr/lib/xorg/modules/dri/i965_dri.so)
==4320==    by 0xAF1F14D: brw_upload_state (in /usr/lib/xorg/modules/dri/i965_dri.so)
==4320==    by 0xAF12122: brw_draw_prims (in /usr/lib/xorg/modules/dri/i965_dri.so)
==4320==    by 0xB256824: vbo_exec_vtx_flush (in /usr/lib/xorg/modules/dri/libdricore.so)
==4320==    by 0xB2523BB: vbo_exec_FlushVertices_internal (in /usr/lib/xorg/modules/dri/libdricore.so)
==4320==    by 0xB252411: vbo_exec_FlushVertices (in /usr/lib/xorg/modules/dri/libdricore.so)
==4320==    by 0xB195A3D: _mesa_PopAttrib (in /usr/lib/xorg/modules/dri/libdricore.so)
==4320==    by 0x8DF0F02: __glXDisp_Render (in /usr/lib/xorg/modules/extensions/libglx.xorg)
==4320==    by 0x8DF517F: __glXDispatch (in /usr/lib/xorg/modules/extensions/libglx.xorg)
==4320==  Address 0x126a8b80 is 0 bytes after a block of size 16,368 alloc'd
==4320==    at 0x4C23E03: malloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==4320==    by 0x9A97A64: do_bo_emit_reloc (in /usr/lib/libdrm_intel.so.1.0.0)
==4320==    by 0x9A97B9C: drm_intel_gem_bo_emit_reloc (in /usr/lib/libdrm_intel.so.1.0.0)
==4320==    by 0xAED3234: intel_batchbuffer_emit_reloc (in /usr/lib/xorg/modules/dri/i965_dri.so)
==4320==    by 0xAF191DB: upload_binding_table_pointers (in /usr/lib/xorg/modules/dri/i965_dri.so)
==4320==    by 0xAF1F14D: brw_upload_state (in /usr/lib/xorg/modules/dri/i965_dri.so)
==4320==    by 0xAF12122: brw_draw_prims (in /usr/lib/xorg/modules/dri/i965_dri.so)
==4320==    by 0xB255EF6: vbo_exec_DrawArrays (in /usr/lib/xorg/modules/dri/libdricore.so)
==4320==    by 0x8DF67A3: __glXDisp_DrawArrays (in /usr/lib/xorg/modules/extensions/libglx.xorg)
==4320==    by 0x8DF0F02: __glXDisp_Render (in /usr/lib/xorg/modules/extensions/libglx.xorg)
==4320==    by 0x8DF517F: __glXDispatch (in /usr/lib/xorg/modules/extensions/libglx.xorg)
==4320==    by 0x446293: ??? (in /usr/bin/Xorg)

which is simply due to only allocating space for the pointers and not
the structs themselves. D'oh.

Reported-by: Thomas Bächler <thomas@archlinux.org>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>