mfd: bcm590xx: Add PMU ID/revision parsing function

mfd: bcm590xx: Add PMU ID/revision parsing function

The BCM590xx PMUs have two I2C registers for reading the PMU ID
and revision. The revision is useful for subdevice drivers, since
different revisions may have slight differences in behavior (for
example - BCM59054 has different regulator configurations for
revision A0 and A1).

Check the PMU ID register and make sure it matches the DT compatible.
Fetch the digital and analog revision from the PMUREV register
so that it can be used in subdevice drivers.

Also add some known revision values to bcm590xx.h, for convenience
when writing subdevice drivers.

Signed-off-by: Artur Weber <aweber.kernel@gmail.com>
Reviewed-by: Stanislav Jakubek <stano.jakubek@gmail.com>
Link: https://lore.kernel.org/r/20250515-bcm59054-v9-4-14ba0ea2ea5b@gmail.com
Signed-off-by: Lee Jones <lee@kernel.org>