gpio: qpnp-pin: Fix constraint checking for mode

GPIOs has only three modes where as MPP has seven. Change the
constraint check to check for the appropriate value based on the
pin type.

Change-Id: I53c85b4a5e852ef3b9d5dbe939a496053fa26197
Signed-off-by: Michael Bohan <mbohan@codeaurora.org>