Improve sparc_init_modes readability

        * config/sparc/sparc.c (sparc_init_modes): Hoist GET_MODE_SIZE
        computation to the top of the loop.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@209637 138bc75d-0d04-0410-961f-82ee72b054a4