boards: fix max frequency for IS25WP flash chips

IS25WP flash chips support 133MHz only when P[6:3] is programmed, which
will not occur during the SFDP probe sequence used in the FlexSPI nor
driver. With the default P[6:3] value, the best frequency supported for
read instruction 0xEB is 104MHz, so set this for all boards using this
flash chip with the FlexSPI nor driver.

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