soc: altmode: Add debugfs nodes to send PAN EN and PAN ACK

Add debugfs nodes to send Pin Assignment Notifications Enable (PAN EN)
and Acknowledgment (ACK) commands manually if needed, to aid in
debugging situations where it is unclear whether clients are sending
these commands synchronously as per design.

Change-Id: I7a68d676df86cbf6952158202c8e4958db032d5b
Signed-off-by: Guru Das Srinagesh <gurus@codeaurora.org>