input: touchpanel: Add power control to GT9xx driver

Add power initialization  function to request internal and external
LDO depends on device tree configuration. Add power control function
to enable and disable device power.

  This patch is propagated from 3.4 kernel
    commit: 6a71b4f8a752f0fd65e207c0e9fab386e5d72010
    input: touchpanel: Add power control to GT9xx driver

Change-Id: If063900f8cd61c36c4b200d781c68e742cd6bbaf
Signed-off-by: Bingzhe Cai <bingzhec@codeaurora.org>
Signed-off-by: Sudhakar Manapati <smanap@codeaurora.org>