net: stmmac: SDx55: add pps signal and interrupts support

Add ioctl support to handle and generate pps siganal & interrupt.
Add device nodes for pps interrupts to interact with user space.

Change-Id: I401326443e69bfd0fb37986004bdc47f41dc57b7
Signed-off-by: Sneh Shah <snehshah@codeaurora.org>