ARM: dma-mapping: NULLify dev->archdata.mapping pointer on detach
ARM: dma-mapping: NULLify dev->archdata.mapping pointer on detach

The current code only clobbers a local variable, so the device is left
with a stale mapping pointer.

Cc: Hiroshi Doyu <7e37d737f0c384c0dce297667d084735fade9098@nvidia.com>
Signed-off-by: Will Deacon <b913f13ef92ac157955c954ccaaff7be065faba4@arm.com>
Acked-by: Hiroshi Doyu <7e37d737f0c384c0dce297667d084735fade9098@nvidia.com>
Signed-off-by: Marek Szyprowski <2a0259761cc3e88db42be5300c1579a67c77e65e@samsung.com>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs