iommu/exynos: Fix build errors

Commit 25e9d28d (ARM: EXYNOS: remove system mmu initialization from
exynos tree) removed arch/arm/mach-exynos/mach/sysmmu.h header without
removing remaining use of it from exynos-iommu driver, thus causing a
compilation error.

This patch fixes the error by removing respective include line
from exynos-iommu.c.

Use of __pa and __va macro is changed to virt_to_phys and phys_to_virt
which are recommended in driver code. printk formatting of physical
address is also fixed to %pa.

Also System MMU driver is changed to control only a single instance
of System MMU at a time. Since a single instance of System MMU has only
a single clock descriptor for its clock gating, single address range
for control registers, there is no need to obtain two or more clock
descriptors and ioremaped region.

CC: Tomasz Figa <t.figa@samsung.com>
Signed-off-by: Cho KyongHo <pullip.cho@samsung.com>
Signed-off-by: Shaik Ameer Basha <shaik.ameer@samsung.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>