mfd: ab8500-debugfs: Remove extraneous curly brace

Clang errors:

drivers/mfd/ab8500-debugfs.c:1526:2: error: non-void function does not return a value [-Werror,-Wreturn-type]
}
^
drivers/mfd/ab8500-debugfs.c:1528:2: error: expected identifier or '('
return 0;
^
drivers/mfd/ab8500-debugfs.c:1529:1: error: extraneous closing brace ('}')
}
^
3 errors generated.

The cleanup in ab8500_interrupts_show left a curly brace around, remove
it to fix the error.

Fixes: 886c8121659d ("mfd: ab8500-debugfs: Remove the racy fiddling with irq_desc")
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>