[mips] Remove R_MIPS_GOT which isn't used and shares the same number as R_MIPS_GOT16

Unlike my previous commit, don't try to remove the corresponding VK_Mips_GOT yet
even though it shares the same assembly text since that is used.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@205196 91177308-0d34-0410-b5e6-96231b3b80d8