bbai64: fixups for pcie m.2 internal clock source + leds

Created by: nmenon

Fixups include:

• gpio reset for PCIe
• we should'nt be telling serdes clock mux to mux external clock when we are trying to use internal clock
• lets have some led blinky that tells us the system is alive and not dead.

Test log: https://gist.github.com/nmenon/679e9843f0d5f1bbb50e24f150e0235c