spi: tegra114: flush fifos

spi: tegra114: flush fifos

BugLink: https://bugs.launchpad.net/bugs/1863019
[ Upstream commit c4fc9e5b28ff787e35137c2cc13316bb11d7657b ]

Fixes: Flush TX and RX FIFOs before start of new transfer and on FIFO
overflow or underrun errors.

Signed-off-by: Sowjanya Komatineni <skomatineni@nvidia.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>