platform: msm: make qpnp-power-on depend on CONFIG_INPUT

The qpnp-power-on driver calls functions which are defined in
drivers/input/input.c.  However, this file is only compiled if
CONFIG_INPUT is set and there are no stub definitions for the
exported functions in a header file.  Therefore, add
CONFIG_INPUT as a dependency for CONFIG_QPNP_POWER_ON in Kconfig
in order to capture the compilation dependency.

Change-Id: I38c3132b44e83095483c959d99c7c1be72f3e18e
Signed-off-by: David Collins <collinsd@codeaurora.org>