power: qpnp-fg-gen3: Use DMA grant interrupt efficiently

Currently, DMA grant interrupt is handled for both rising and
falling edge even though only rising edge is used for completing
the DMA grant request. Configure DMA grant interrupt only for
rising edge so that it can be used efficiently by reducing
the interrupt handling.

While at it, add support to dump registers when a DMA grant
request times out. This will be helpful for debugging when such
an event happens.

Change-Id: I7666cef6c2f0aa93dece463b905b8d7aa940be39
Signed-off-by: Subbaraman Narayanamurthy <subbaram@codeaurora.org>