scsi: ufs: exynos: Fix the maximum segment size

Prepare for enabling DMA clustering and also for supporting PAGE_SIZE !=
4096 by declaring explicitly that the maximum segment size is 4096 bytes
for Exynos UFS host controllers. Add this code in
exynos_ufs_hce_enable_notify() such that it happens after scsi_host_alloc()
and before __scsi_init_queue() is called by the LUN scanning code.

Cc: Alim Akhtar <alim.akhtar@samsung.com>
Cc: Kiwoong Kim <kwmad.kim@samsung.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Alim Akhtar <alim.akhtar@samsung.com>
Tested-by: Alim Akhtar <alim.akhtar@samsung.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>