Please revert upstream commit e4849aff1e16 ("MIPS: SiByte: Enable swiotlb ...") in v4.4.y and v4.14.y

[Guenter Roeck <linux@xxxxxxxxxxxx>]

Upstream commit e4849aff1e16 ("MIPS: SiByte: Enable swiotlb for SWARM,
LittleSur and BigSur") results in build failures in v4.4.y and v4.14.y.

make bigsur_defconfig:

warning: (SIBYTE_SWARM && SIBYTE_SENTOSA && SIBYTE_BIGSUR && SWIOTLB_XEN && AMD_IOMMU) selects SWIOTLB which has unmet direct dependencies (CAVIUM_OCTEON_SOC || MACH_LOONGSON64 && CPU_LOONGSON3 || NLM_XLP_BOARD || NLM_XLR_BOARD)
warning: (SIBYTE_SWARM && SIBYTE_SENTOSA && SIBYTE_BIGSUR && SWIOTLB_XEN && AMD_IOMMU) selects SWIOTLB which has unmet direct dependencies (CAVIUM_OCTEON_SOC || MACH_LOONGSON64 && CPU_LOONGSON3 || NLM_XLP_BOARD || NLM_XLR_BOARD)

and the actual build:

lib/swiotlb.o: In function `swiotlb_tbl_map_single':
(.text+0x1c0): undefined reference to `iommu_is_span_boundary'
Makefile:1021: recipe for target 'vmlinux' failed

Please revert.

Thanks,
Guenter