ACPI: thinkpad-acpi: skip blanks before the data when parsing sysfs

Skip blanks not just at the tail of sysfs writes, but also at the head.
Signed-off-by: Henrique de Moraes Holschuh <hmh@hmh.eng.br>
Signed-off-by: Len Brown <len.brown@intel.com>

drivers/misc/thinkpad_acpi.c

@@ -709,6 +709,8 @@ static int parse_strtoul(const char *buf,
 {
 	char *endp;
 
+	while (*buf && isspace(*buf))
+		buf++;
 	*value = simple_strtoul(buf, &endp, 0);
 	while (*endp && isspace(*endp))
 		endp++;