The MX23 has different handling of the SSP clock and GPMI NAND clock sources,
add necessary quirks into the clock code to properly handle these.

Signed-off-by: Marek Vasut <marex@denx.de>
Signed-off-by: Otavio Salvador <otavio@ossystems.com.br>
Cc: Fabio Estevam <fabio.estevam@freescale.com>
Cc: Stefano Babic <sbabic@denx.de>