i965: increase the brw eu instruction store size dynamically

i965: increase the brw eu instruction store size dynamically

Here is the final patch to enable dynamic eu instruction store size:
increase the brw eu instruction store size dynamically instead of just
allocating it statically with a constant limit. This would fix something
that 'GL_MAX_PROGRAM_INSTRUCTIONS_ARB was 16384 while the driver would
limit it to 10000'.

v2: comments from ken, do not hardcode the eu limit to (1024 * 1024)

Signed-off-by: Yuanhan Liu <yuanhan.liu@linux.intel.com>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Eric Anholt <eric@anholt.net>