i965/fs: Change the type of booleans to UD and emit correct immediates

i965/fs: Change the type of booleans to UD and emit correct immediates

Before, we used the a signed d-word for booleans and the immedates we
emitted varried between signed and unsigned.  This commit changes the type
to unsigned (I think that makes more sense) and makes immediates more
consistent.  This allows copy propagation to work better cleans up some
instructions.

total instructions in shared programs: 5473519 -> 5465864 (-0.14%)
instructions in affected programs:     432849 -> 425194 (-1.77%)
GAINED:                                27
LOST:                                  0

Signed-off-by: Jason Ekstrand <jason.ekstrand@intel.com>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Matt Turner <mattst88@gmail.com>