drivers: flash: flash_mcux_flexspi_nor: fix IS25WP flash support

Some NXP boards program the read parameters bits (P[6:3]) within the
IS25WP flash device during init, which will result in JESD216 probe
commands failing (as the number of dummy cycles will be incorrect). Add
handling to force these volatile bits to their default value to the
flexspi flash driver.

Signed-off-by: Daniel DeGrasse <daniel.degrasse@nxp.com>