tty: remove platform_sysrq_reset_seq

The platform_sysrq_reset_seq code was intended as a way for an embedded
platform to provide its own sysrq sequence at compile time. After over two
years, nobody has started using it in an upstream kernel, and the platforms
that were interested in it have moved on to devicetree, which can be used
to configure the sequence without requiring kernel changes. The method is
also incompatible with the way that most architectures build support for
multiple platforms into a single kernel.

Now the code is producing warnings when built with gcc-5.1:

drivers/tty/sysrq.c: In function 'sysrq_init':
drivers/tty/sysrq.c:959:33: warning: array subscript is above array bounds [-Warray-bounds]
   key = platform_sysrq_reset_seq[i];

We could fix this, but it seems unlikely that it will ever be used, so
let's just remove the code instead. We still have the option to pass the
sequence either in DT, using the kernel command line, or using the
/sys/module/sysrq/parameters/reset_seq file.

Fixes: 154b7a4 ("Input: sysrq - allow specifying alternate reset sequence")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

drivers/tty/sysrq.c

@@ -55,9 +55,6 @@
 static int __read_mostly sysrq_enabled = CONFIG_MAGIC_SYSRQ_DEFAULT_ENABLE;
 static bool __read_mostly sysrq_always_enabled;
 
-unsigned short platform_sysrq_reset_seq[] __weak = { KEY_RESERVED };
-int sysrq_reset_downtime_ms __weak;
-
 static bool sysrq_on(void)
 {
 	return sysrq_enabled || sysrq_always_enabled;
@@ -568,6 +565,7 @@ void handle_sysrq(int key)
 EXPORT_SYMBOL(handle_sysrq);
 
 #ifdef CONFIG_INPUT
+static int sysrq_reset_downtime_ms;
 
 /* Simple translation table for the SysRq keys */
 static const unsigned char sysrq_xlate[KEY_CNT] =
@@ -948,23 +946,8 @@ static bool sysrq_handler_registered;
 
 static inline void sysrq_register_handler(void)
 {
-	unsigned short key;
 	int error;
-	int i;
-
-	/* First check if a __weak interface was instantiated. */
-	for (i = 0; i < ARRAY_SIZE(sysrq_reset_seq); i++) {
-		key = platform_sysrq_reset_seq[i];
-		if (key == KEY_RESERVED || key > KEY_MAX)
-			break;
-
-		sysrq_reset_seq[sysrq_reset_seq_len++] = key;
-	}
 
-	/*
-	 * DT configuration takes precedence over anything that would
-	 * have been defined via the __weak interface.
-	 */
 	sysrq_of_get_keyreset_config();
 
 	error = input_register_handler(&sysrq_handler);