Revert "regulator: pca9450: Convert to use regulator_set_ramp_delay_regmap"

This reverts commit b3a9c408 which is
commit 4c4fce17 upstream.

It is part of a series that breaks the Android kernel abi and can be
safely reverted at this point in time.  If it needs to come back in the
future, it can be done so in an abi-safe way.

Bug: 161946584
Change-Id: I20ea532f38c565713dc4a29ad0a35916f851aebe
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>