riscv: Fixed wrong register in XIP_FIXUP_FLASH_OFFSET macro

During the refactoring, a bug was introduced in the rarly used
XIP_FIXUP_FLASH_OFFSET macro.

Fixes: bee7fbc38579 ("RISC-V CPU Idle Support")
Fixes: e7681beba992 ("RISC-V: Split out the XIP fixups into their own file")

Signed-off-by: Frederik Haxel <haxel@fzi.de>
Link: https://lore.kernel.org/r/20231212130116.848530-3-haxel@fzi.de
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

RISC-V: Split out the XIP fixups into their own file

This was broken by the original refactoring (as the XIP definitions
depend on <asm/pgtable.h>) and then more broken by the merge (as I
accidentally took the old version). This fixes both breakages, while
also pulling this out of <asm/asm.h> to avoid polluting most assembly
files with the XIP fixups.

Fixes: bee7fbc38579 ("RISC-V CPU Idle Support")
Fixes: 63b13e64a829 ("RISC-V: Add arch functions for non-retentive suspend entry/exit")
Link: https://lore.kernel.org/r/20220420184056.7886-4-palmer@rivosinc.com
Reviewed-by: Guo Ren <guoren@kernel.org>
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>