sysrq: Remove duplicated sysrq message

The commit 97f5f0cd ("Input: implement SysRq as a separate input
handler") added pr_fmt() definition. It caused a duplicated message
prefix in the sysrq header messages, for example:

[  177.053931] sysrq: SysRq : Show backtrace of all active CPUs
[  742.864776] sysrq: SysRq : HELP : loglevel(0-9) reboot(b) crash(c)

Fixes: 97f5f0cd

 ("Input: implement SysRq as a separate input handler")
Signed-off-by: Petr Mladek <pmladek@suse.com>
Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>