[PATCH] [Patch, microblaze] Added ashrsi3_with_size_opt

Added ashrsi3_with_size_opt pattern to optimize the sra instructions
when the -Os optimization is used. lshrsi3_with_size_opt is
being removed as it has conflicts with unsigned int variables

Signed-off-by:Nagaraju Mekala <nmekala@xilix.com>