iommu/exynos: Enable default VM instance on SysMMU v7

In order to enable SysMMU v7 with VM register layout, at least the
default VM instance (n=0) must be enabled, in addition to enabling the
SysMMU itself. To do so, add corresponding write to MMU_CTRL_VM[0]
register, before writing to MMU_CTRL register.

Signed-off-by: Sam Protsenko <semen.protsenko@linaro.org>
Acked-by: Marek Szyprowski <m.szyprowski@samsung.com>
Link: https://lore.kernel.org/r/20220714165550.8884-7-semen.protsenko@linaro.org
Signed-off-by: Joerg Roedel <jroedel@suse.de>