[RISCV] Exclude vector callee saved registers from RISCVRegisterInfo::needsFrameBaseReg

The vector callee saved registers shouldn't affect the frame pointer
offset so we don't want to consider them.

I've listed the GPR, FPR32, and FPR64 register classes explicitly
because getMinimalPhysRegClass is slow and this function is called
frequently. So explicitly listing the interesting classs should be
a compile time improvement.