phy: exynos-mipi-video: Drop support for direct access to PMU

There is no need to support access to the PMU through memory ioresource
as now access through PMU regmap should only be used.

Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>