calculate the txfm_cache difference first as both values may be
INT64_MAX with the intent that they cancel each other out.
Change-Id: I214d072458e1b24f60289974e6302af1aff7b66c
rd_pick_intra4x4mby_modes / rd_pick_intra8x8mby_modes would both use the
input value of 'rate_y' in the return calculation. In many places this
value is uninitialized. Remove the unneeded sum.
Change-Id: Icbd3df685303000301e69291c0ebc06f74bd548d