powerpc/ioda: Set "read" permission when "write" is set

powerpc/ioda: Set "read" permission when "write" is set

Quite often drivers set only "write" permission assuming that this
includes "read" permission as well and this works on plenty of
platforms. However IODA2 is strict about this and produces an EEH when
"read" permission is not set and reading happens.

This adds a workaround in the IODA code to always add the "read" bit
when the "write" bit is set.

Fixes: 10b35b2b7485 ("powerpc/powernv: Do not set "read" flag if direction==DMA_NONE")
Cc: [email protected] # 4.2+
Cc: Benjamin Herrenschmidt <[email protected]>
Signed-off-by: Alexey Kardashevskiy <[email protected]>
Tested-by: Douglas Miller <[email protected]>
Signed-off-by: Michael Ellerman <[email protected]>