iommu/arm-smmu: fix some checkpatch issues

Fix some issues reported by checkpatch.pl. Mostly whitespace, but also
includes min=>min_t, kzalloc=>kcalloc, and kmalloc=>kmalloc_array.

The only issue I'm leaving alone is:

    arm-smmu.c:853: WARNING: line over 80 characters
    #853: FILE: arm-smmu.c:853:
    +                     (MAIR_ATTR_WBRWA << MAIR_ATTR_SHIFT(MAIR_ATTR_IDX_CACHE)) |

since it seems to be a case where "exceeding 80 columns significantly
increases readability and does not hide information."
(Documentation/CodingStyle).

Signed-off-by: Mitchel Humpherys <mitchelh@codeaurora.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>