riscv: Fix early alternative patching

Now that the text to patch is located using a relative offset from the
alternative entry, the text address should be computed without applying
the kernel mapping offset, both before and after VM setup.

Fixes: 8d23e94a ("riscv: switch to relative alternative entries")
Signed-off-by: Samuel Holland <samuel@sholland.org>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Guo Ren <guoren@kernel.org>
Reviewed-by: Jisheng Zhang <jszhang@kernel.org>
Tested-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20230212021534.59121-2-samuel@sholland.org


Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>