tests: drivers: add flexio pwm and spi support for ke17z

pwm: pwm_api: update testcase.yaml and add new overlay configuration
to support flexio pwm driver.
spi: spi_loopback: update testcase.yaml and add new overlay
configuration to support flexio spi driver.

Signed-off-by: Anke Xiao <anke.xiao@nxp.com>