spi: zynq: missing break statement

There is a missing break statement here so selecting both only selects
upper.

Fixes: dfe11a11 ('spi: Add support for Zynq Ultrascale+ MPSoC GQSPI controller')
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Michal Simek <michal.simek@xilinx.com>
Signed-off-by: Mark Brown <broonie@kernel.org>