mmc: cavium: fix swiotlb buffer is full

commit 43cd07f68ff2ed82ccb6328262c4c44bf5adbbd5 from
git@git.assembla.com:cavium/WindRiver.linux.git

When using iommu.passthrough=1, the maximum dma size is
limited by swiotlb size.  OcteonTX platforms do not need
swiotlb, but iommu-passthru (a useful development option)
forces it.  So adapt the size cap from Yoshihiro Shimoda's
commit e90e8da7 ("mmc: tmio: fix swiotlb buffer is full").

Passthru reduces peak i/o rate on large requests, but could
improve random filesystem performance slightly on some loads
(hdparm -t down ~5%, mke2fs up ~15%)

To get back some of that performance loss, the irqs are
specified as non-threaded, as the persistent state is all
contained in host->current_req, so no thread context needed.

Signed-off-by: Peter Swain <pswain@marvell.com>

Change-Id: I256729f8ff0ef194e6c57dda000c7341cac446f4
Reviewed-on: https://sj1git1.cavium.com/3944


Reviewed-by: Chandrakala Chavva <Chandrakala.Chavva@cavium.com>
Reviewed-by: Sunil Kovvuri Goutham <Sunil.Goutham@cavium.com>
Signed-off-by: Sujeet Baranwal <sbaranwal@marvell.com>
Reviewed-on: https://sj1git1.cavium.com/8550


Tested-by: Sunil Kovvuri Goutham <Sunil.Goutham@cavium.com>
Reviewed-by: Chandrakala Chavva <cchavva@marvell.com>
Signed-off-by: Kevin Hao <kexin.hao@windriver.com>