regulator: qpnp-lcdb: Correct the get_voltage calculation

NCP/LDO output voltage register is of 5 bits [4:0] only. The
current calculation uses [7:0] which causes a incorrect value
to be reported. Fix it.

Change-Id: Idd00f5364e6bac7b086f4ca606c592e57d8bb24a
Signed-off-by: Kiran Gunda <kgunda@codeaurora.org>