firmware: turris-mox-rwtm: small white space cleanup

This patch deletes a stray tab.

Cc: Gregory CLEMENT <gregory.clement@bootlin.com>
Cc: Colin King <colin.king@canonical.com>
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Marek Behún <marek.behun@nic.cz>
Signed-off-by: Gregory CLEMENT <gregory.clement@bootlin.com>