iommu: arm-smmu: Preallocate memory for map only on failure

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

In order to avoid page allocation failure of order 0 during the
smmu map operation, the existing implementation preallocates
the required memory using GFP_KERNEL so as to make sure that
there is sufficient page table memory available and the atomic
allocation succeeds during the map operation.This might not be
necessary for every single map call as the atomic allocation
might succeed most of the time.Hence preallocate the necessary
memory only when the map operation fails due to insufficient
memory and again retry the map operation with the preallocated
memory.This solution applies only to map calls made from a
non-atomic context.

Change-Id: I417f311c2224eb863d6c99612b678bbb2dd3db58
Signed-off-by: Swathi Sridhar <swatsrid@codeaurora.org>