firmware_loader: Fix a typo ("syfs" -> "sysfs")

"sysfs" was misspelled in a comment and a log message.

Signed-off-by: Jonathan Neuschäfer <j.neuschaefer@gmx.net>
Reviewed-by: Mukesh Ojha <mojha@codeaurora.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>