ARM: omap: pmic-cpcap: do not mess around without CPCAP or OMAP4

The late init call just writes to omap4 registers as soon as
CONFIG_MFD_CPCAP is enabled without checking whether the
cpcap driver is actually there or the SoC is indeed an
OMAP4.
Rather do these things only with the right device combination.

Fixes booting the BT200 with said configuration enabled and non-factory
X-Loader and probably also some surprising behavior on other devices.

Fixes: c145649b ("ARM: OMAP2+: Configure voltage controller for cpcap to low-speed")
CC: stable@vger.kernel.org
Signed-off-by: Andreas Kemnade <andreas@kemnade.info>
Reivewed-by: Tony Lindgren <tony@atomide.com>
Link: https://lore.kernel.org/r/20250331144439.769697-1-andreas@kemnade.info


Signed-off-by: Kevin Hilman <khilman@baylibre.com>