mfd: ab8500-debugfs: Fix incompatible types in comparison expression issue

Smatch reports:

drivers/mfd/ab8500-debugfs.c:1804:20: error: incompatible types in comparison expression (different type sizes):
drivers/mfd/ab8500-debugfs.c:1804:20: unsigned int *
drivers/mfd/ab8500-debugfs.c:1804:20: unsigned long *

This is due to mixed types being compared in a min() comparison. Fix
this by treating values as signed and casting them to the same type
as the receiving variable.

Cc: Linus Walleij <[e-mail]>
Signed-off-by: Lee Jones <[e-mail]>

drivers/mfd/ab8500-debugfs.c

···
 	int buf_size, ret;
 
 	/* Get userspace string and assure termination */
-	buf_size = min(count, (sizeof(buf)-1));
+	buf_size = min((int)count, (int)(sizeof(buf)-1));
 	if (copy_from_user(buf, user_buf, buf_size))
 		return -EFAULT;
 	buf[buf_size] = 0;