[RISCV] Replace && with ||. Spotted by coverity.

We should be exiting when the shift amount is greater than
the bit width regardless of whether it is a power of 2.

Reported by Simon Pilgrim here https://reviews.llvm.org/D96661

This requires getting a shift amount that is out of bounds that
wasn't already optimized by SelectionDAG. This would be pretty
trick to construct a test for.

Or it would require a non-power of 2 shift amount and a mask
that has runs of ones and zeros of the next lowest power of 2 from
that shift amount. I tried a little to produce a test for this,
but didn't get it to work.