Split the SATA clock enabling function and add PCI express clock
enabling function. The SATA clock enabling function starts up the
100MHz SATA reference PLL in ENET_PLL register, but the code can
be re-used to enable the 125MHz PCIe reference in ENET_PLL, so pull
this code into separate function. Moreover, add the PCIe clock
enabling code.

Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Albert Aribaud <albert.u.boot@aribaud.net>
Cc: Eric Nelson <eric.nelson@boundarydevices.com>
Cc: Fabio Estevam <fabio.estevam@freescale.com>
Cc: Stefano Babic <sbabic@denx.de>
Acked-by: Jagannadha Sutradharudu Teki <jagannadh.teki@gmail.com>