When accessing the MCA MSRs, the MCA bank number gets multiplied by 4 and added to the IA32_MC0_* define to get the MSR number. Add a macro that already does this calculation to avoid open coding this repeatedly. Change-Id: I2de753b8c8ac8dcff5a94d5bba43aa13bbf94b99 Signed-off-by: Felix Held <felix-coreboot@felixheld.de> Reviewed-on: https://review.coreboot.org/c/coreboot/+/56243 Reviewed-by: Raul Rangel <rrangel@chromium.org> Tested-by: build bot (Jenkins) <no-reply@coreboot.org>