thermal: intel: BXT_PMIC: select REGMAP instead of depending on it

thermal: intel: BXT_PMIC: select REGMAP instead of depending on it

[ Upstream commit b8c8e14a7712a6922ef3333eab6d8f9b5c1372b5 ]

REGMAP is a hidden (not user visible) symbol. Users cannot set it
directly thru "make *config", so drivers should select it instead of
depending on it if they need it.

Consistently using "select" or "depends on" can also help reduce
Kconfig circular dependency issues.

Therefore, change the use of "depends on REGMAP" to "select REGMAP".

Fixes: a6b647067f68 ("thermal: add Intel BXT WhiskeyCove PMIC thermal driver")
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>