video: exynos_mipi_dsim: Use the generic PHY driver

Use the generic PHY API instead of the platform callback
for the MIPI DSIM DPHY enable/reset control.

Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Acked-by: Felipe Balbi <balbi@ti.com>
Acked-by: Donghwa Lee <dh09.lee@samsung.com>
Acked-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>