iommu: arm-smmu: Preallocate memory for map operation

page allocation failure: order:0, mode:0x2088020(GFP_ATOMIC|__GFP_ZERO)
 Call trace:
 [<ffffff80080f15c8>] dump_backtrace+0x0/0x248
 [<ffffff80080f1894>] show_stack+0x18/0x28
 [<ffffff8008484984>] dump_stack+0x98/0xc0
 [<ffffff8008231b0c>] warn_alloc+0x114/0x134
 [<ffffff8008231f7c>] __alloc_pages_nodemask+0x3e8/0xd30
 [<ffffff8008232b2c>] alloc_pages_exact+0x4c/0xa4
 [<ffffff800866bec4>] arm_smmu_alloc_pages_exact+0x188/0x1bc
 [<ffffff8008664b28>] io_pgtable_alloc_pages_exact+0x30/0xa0
 [<ffffff8008664ff8>] __arm_lpae_alloc_pages+0x40/0x1c8
 [<ffffff8008665cb4>] __arm_lpae_map+0x224/0x3b4
 [<ffffff8008665b98>] __arm_lpae_map+0x108/0x3b4
 [<ffffff8008666474>] arm_lpae_map+0x78/0x9c
 [<ffffff800866aed4>] arm_smmu_map+0x80/0xdc
 [<ffffff800866015c>] iommu_map+0x118/0x284
 [<ffffff8008c66294>] cam_smmu_alloc_firmware+0x188/0x3c0
 [<ffffff8008cc8afc>] cam_icp_mgr_hw_open+0x88/0x874
 [<ffffff8008cca030>] cam_icp_mgr_acquire_hw+0x2d4/0xc9c
 [<ffffff8008c5fe84>] cam_context_acquire_dev_to_hw+0xb0/0x26c
 [<ffffff8008cd0ce0>] __cam_icp_acquire_dev_in_available+0x1c/0xf0
 [<ffffff8008c5ea98>] cam_context_handle_acquire_dev+0x5c/0x1a8
 [<ffffff8008c619b4>] cam_node_handle_ioctl+0x30c/0xdc8
 [<ffffff8008c62640>] cam_subdev_compat_ioctl+0xe4/0x1dc
 [<ffffff8008bcf8bc>] subdev_compat_ioctl32+0x40/0x68
 [<ffffff8008bd3858>] v4l2_compat_ioctl32+0x64/0x1780

Preallocate the required memory using GFP_KERNEL when the iommu
domain allows sleep.

Change-Id: I96194a4fabd21cc1d685e4f12afe8fbdd4768ac2
Signed-off-by: Patrick Daly <pdaly@codeaurora.org>