net/tftp.c: cosmetic: do not initialise statics to 0 or NULL

This removes the following checkpatch issue:
 - ERROR: do not initialise statics to 0 or NULL

Signed-off-by: Luca Ceresoli <luca.ceresoli@comelit.it>
Cc: Wolfgang Denk <wd@denx.de>
1 file changed