OMAPDSS: HDMI: move irq & phy pwr handling

HDMI IRQ handling was moved into hdmi_phy.c when restructuring the HDMI
driver. While this worked fine, it's not correct.

The HDMI IRQ handling should be either in the hdmi_wp, or in the main
hdmi driver. This patch moves the handling to the main hdmi driver, as I
feel it's a more appropriate choice.

This move also requires changing the handling of the PHY power, as that
was partly handled in the IRQ handler. The PHY power is handled via the
WP module. An option would be to give HDMI PHY driver function pointers
that it could use to manage the PHY power, but as the PHY power is not
needed to access the PHY registers, the handling was also moved to the
main HDMI driver. This could be changed later if need be.

Note that there's slightly similar power issue with the PLL: the HDMI
PLLs power is also handled via the WP module. For now, the PLL power
handling is still done inside the PLL driver.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>