mfd: da9055: Drop "select PMIC_DA9055"

The Kconfig entry for DA9055 PMIC Support selects PMIC_DA9055. That was
probably inspired by the similar select statement in the entry for
DA9052/53 PMIC with I2C. But the DA9055 PMIC only comes in an I2C
variant and its driver doesn't need a separate Kconfig symbol for shared
code. In any case, this select can be dropped as PMIC_DA9055 doesn't
exist.

Signed-off-by: Paul Bolle <pebolle@tiscali.nl>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>