drivers: spi_mcux_lpspi: fix baudrate change when switching devices

When configuring an LPSPI module for a new device with different baud rate,
the module needs to be disabled for the baud rate change to take effect.
This adds the necessary call to LPSPI_Enable before initializing the
module.

Fixes #51177

Signed-off-by: Jonas Otto <jonas@jonasotto.com>