ntb_hw_switchtec: Fix bug with more than 32 partitions

ntb_hw_switchtec: Fix bug with more than 32 partitions

[ Upstream commit 7ff351c86b6b258f387502ab2c9b9d04f82c1c3d ]

Switchtec could support as mush as 48 partitions, but ffs & fls are
for 32 bit argument, in case of partition index larger than 31, the
current code could not parse the peer partition index correctly.
Change to the 64 bit version __ffs64 & fls64 accordingly to fix this
bug.

Fixes: 3df54c870f52 ("ntb_hw_switchtec: Allow using Switchtec NTB in multi-partition setups")
Signed-off-by: Wesley Sheng <wesley.sheng@microchip.com>
Signed-off-by: Kelvin Cao <kelvin.cao@microchip.com>
Signed-off-by: Jon Mason <jdmason@kudzu.us>
Signed-off-by: Sasha Levin <sashal@kernel.org>