serial: msm: Cleanup register naming

serial: msm: Cleanup register naming

Some of the register definitions are inconsistently named (likely copied
as-is from Qualcomm's Little Kernel/LK bootloader, which uses the
MSM_BOOT_UART naming scheme). Rename them to be in line with the other
register definitions and move them up to be next to the related register.

No functional change.

Signed-off-by: Stephan Gerhold <stephan.gerhold@linaro.org>
Tested-by: Alexey Minnekhanov <alexeymin@minlexx.ru>
Acked-by: Sumit Garg <sumit.garg@oss.qualcomm.com>
Link: https://lore.kernel.org/r/20250908-db410c-autoboot-fixes-v2-3-316ed98e0143@linaro.org
Signed-off-by: Casey Connolly <kcxt@postmarketos.org>