spi: cadence: Fix busy cycles calculation

If xSPI is in x2/x4/x8 mode to calculate busy
cycles, busy bits count must be divided by the number
of lanes.
If opcommand is using 8 busy bits, but SPI is
in x4 mode, there will be only 2 busy cycles.

Signed-off-by: Witold Sadowski <wsadowski@marvell.com>
Reviewed-by: Chandrakala Chavva <cchavva@marvell.com>
Reviewed-by: Sunil Kovvuri Goutham <sgoutham@marvell.com>
Link: https://lore.kernel.org/r/20221219144254.20883-2-wsadowski@marvell.com


Signed-off-by: Mark Brown <broonie@kernel.org>