net: tftp: Remove tftp_init_load_addr error path

net: tftp: Remove tftp_init_load_addr error path

tftp_init_load_addr() always returns 0 since commit af45c84871e4 ("tftp:
rework the logic to validate the load address"), so we don't need to
check if it failed and can remove the error handling.
Also change tftp_init_load_addr() to static void since the return value
is now unused.

Signed-off-by: Leonard Anderweit <l.anderweit@phytec.de>
Reviewed-by: Yannic Moog <y.moog@phytec.de>