pinctrl: Fix kernel-doc

Fix function name in pinctrl-single.c kernel-doc comment
to remove a warning found by clang_w1.

drivers/pinctrl/pinctrl-single.c:1523: warning: expecting prototype for
pcs_irq_handle(). Prototype was for pcs_irq_chain_handler() instead.

Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Signed-off-by: Yang Li <yang.lee@linux.alibaba.com>
Link: https://lore.kernel.org/r/1621998464-10918-1-git-send-email-yang.lee@linux.alibaba.com
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>