drivers: pinctrl: Add custom GPIO to PDC pin mapping list support

Add feature support where a user can provide a custom list of TLMM
GPIOs associated with PDC pins for direct connect interrupt support.
This feature is needed because the TLMM GPIO PDC map is fixed per target
which is restrictive for a usecase where a custom list of direct connect
interrupts for GPIOs is needed.

Change-Id: Idc6e07a3405c7900445f25e60d08570f7b350fcc
Signed-off-by: Anant Goel <anantg@codeaurora.org>