Platforms/RaspberryPi: RPi4 PMU interrupts are SPI not PPI

REF: https://github.com/pftf/RPi4/issues/103

Commit 602a7ea1 changed the RPi4 PMU interrupts reported
in GICC to the PPI values recommended by SBSA specification.
This caused the PMU overflow interrupts to stop working.

The RPi documentation (Figure 7, page 111) state that the
PMU interrupts are SPI not PPI: https://www.raspberrypi.org/
documentation/hardware/raspberrypi/bcm2711/rpi_DATA_2711_1p0.pdf

Also, the BSA 1.0 spec (page 24) clarifies hat the PPI values are
recommendations, not requirements:
https://developer.arm.com/documentation/den0094/latest



Fix by reverting to the old SPI values per the RPi spec.

Cc: Leif Lindholm <leif@nuviainc.com>
Cc: Pete Batard <pete@akeo.ie>
Cc: Andrei Warkentin <awarkentin@vmware.com>
Signed-off-by: Samer El-Haj-Mahmoud <Samer.El-Haj-Mahmoud@arm.com>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@arm.com>