Rename from V5A_EN to PMIC_EN.
The name V5A_EN came from Amenia where it controls both
5V_A-Rail and PMIC_EN.
Reef has a separate 5V_A-Rail control (EN_PP5000) and
an another GPIO pin for PMIC_EN.
BUG=chrome-os-partner:53666
BRANCH=none
TEST=buildall pass
Change-Id: Ic5e39b9811a6cf0e968c1d6262b9b9f849268ed4
Signed-off-by: Kevin K Wong <kevin.k.wong@intel.com>
Reviewed-on: https://chromium-review.googlesource.com/354767
Reviewed-by: David Hendricks <dhendrix@chromium.org>