pinctrl: mcp23s08: Fix missing unlock on error in mcp23s08_irq()

pinctrl: mcp23s08: Fix missing unlock on error in mcp23s08_irq()

BugLink: https://bugs.launchpad.net/bugs/1938713
commit 884af72c90016cfccd5717439c86b48702cbf184 upstream.

Add the missing unlock before return from function mcp23s08_irq()
in the error handling case.

v1-->v2:
   remove the "return IRQ_HANDLED" line

Fixes: 897120d41e7a ("pinctrl: mcp23s08: fix race condition in irq handler")
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Zou Wei <zou_wei@huawei.com>
Link: https://lore.kernel.org/r/1623134048-56051-1-git-send-email-zou_wei@huawei.com
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>