regulator: qcom-rpmh: add QCOM_COMMAND_DB dependency

regulator: qcom-rpmh: add QCOM_COMMAND_DB dependency

A built-in regulator driver cannot link against a modular cmd_db driver:

qcom-rpmh-regulator.c:(.text+0x174): undefined reference to `cmd_db_read_addr'

There is already a dependency for RPMh, so add another one of this
type for cmd_db.

Fixes: 34c5aa2666db ("regulator: Kconfig: Fix REGULATOR_QCOM_RPMH dependencies to avoid build error")
Fixes: 46fc033eba42 ("regulator: add QCOM RPMh regulator driver")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20201230145712.3133110-1-arnd@kernel.org
Signed-off-by: Mark Brown <broonie@kernel.org>