[PATCH 4/6] ARM/keystone: move the DMA offset handling under ifdef CONFIG_ARM_LPAE

The DMA offset notifier can only be used if PHYS_OFFSET is at least KEYSTONE_HIGH_PHYS_START, which can't be represented by a 32-bit phys_addr_t. Currently the code compiles fine despite that, a pending change to the DMA offset handling would create a compiler warning for this case. Add an ifdef

[PATCH 4/6] ARM/keystone: move the DMA offset handling under ifdef CONFIG_ARM_LPAE

The DMA offset notifier can only be used if PHYS_OFFSET is at least KEYSTONE_HIGH_PHYS_START, which can't be represented by a 32-bit phys_addr_t. Currently the code compiles fine despite that, a pending change to the DMA offset handling would create a compiler warning for this case. Add an ifdef