pinctrl: Added IRQF_SHARED flag for amd-pinctrl driver

Some of the AMD reference boards used single GPIO line for
multiple devices. So added IRQF_SHARED flag in amd pinctrl driver.

Signed-off-by: Sandeep Singh <Sandeep.Singh@amd.com>
Signed-off-by: Shyam Sundar S K <Shyam-sundar.S-k@amd.com>
cc: Nehal Shah <Nehal-bakulchandra.Shah@amd.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>