modprobe: use buffering line reads (fgets) instead of reads().

modprobe: use buffering line reads (fgets) instead of reads().
libbb: remove reads()

function                                             old     new   delta
include_conf_file_act                                961     980     +19
localcmd                                             282     284      +2
already_loaded                                       155     151      -4
in_cksum                                              58      53      -5
modprobe_main                                       1630    1624      -6
reads                                                129       -    -129
------------------------------------------------------------------------------
(add/remove: 0/1 grow/shrink: 2/3 up/down: 21/-144)          Total: -123 bytes