ACPI / scan: constify first argument of struct acpi_scan_handler::match

One wouldn't expect a "match" function modify the string it searches
for, and indeed the only instance of the struct
acpi_scan_handler::match callback, acpi_pnp_match, can easily be
changed. While there, update its helper matching_id().

This is also preparation for constifying struct acpi_hardware_id::id.

Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
diff --git a/drivers/acpi/acpi_pnp.c b/drivers/acpi/acpi_pnp.c
index c58940b..48fc3ad 100644
--- a/drivers/acpi/acpi_pnp.c
+++ b/drivers/acpi/acpi_pnp.c
@@ -316,7 +316,7 @@
 	{""},
 };
 
-static bool matching_id(char *idstr, char *list_id)
+static bool matching_id(const char *idstr, const char *list_id)
 {
 	int i;
 
@@ -333,7 +333,7 @@
 	return true;
 }
 
-static bool acpi_pnp_match(char *idstr, const struct acpi_device_id **matchid)
+static bool acpi_pnp_match(const char *idstr, const struct acpi_device_id **matchid)
 {
 	const struct acpi_device_id *devid;