cmd_ext2.c: fix compile warnings

Get rid of these warnings:

cmd_ext2.c:247: warning: format '%ld' expects type 'long int', but argument 2 has type 'int'
cmd_ext2.c:248: warning: format '%lX' expects type 'long unsigned int', but argument 3 has type 'int'

Signed-off-by: Wolfgang Denk <wd@denx.de>