spi: nxp_fspi: Fix clock imbalance

The nxp_fspi_default_setup() is only ever called from nxp_fspi_probe(),
where the IP clock are initially disabled. Drop the second disabling of
clock to prevent clock enable/disable imbalance reported by clock core:

"
clk qspi_root_clk already disabled
"

Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Fabio Estevam <festevam@denx.de>
Cc: Peng Fan <peng.fan@nxp.com>
Cc: Stefano Babic <sbabic@denx.de>
Reviewed-by: Peng Fan <peng.fan@nxp.com>