[RISCV] Move the $rs operand of PseudoStore from outs to ins. NFC

This is the data to be stored so it should be an input.

To keep operand order similar between loads and stores, move the temp
register to the first dest operand of floating point loads. Rework
the assembler code accordingly.

This doesn't have any functional effect because this Pseudo is only
used by the assembler which doesn't use ins/outs.

Reviewed By: luismarques

Differential Revision: https://reviews.llvm.org/D107309