* fs/i386/pc/pxe.c (grub_pxe_data): New member block_size.
(grub_pxefs_fs_int): Remove dummy definition.
(grub_pxefs_open): Use data->block_size to store the current block
size setting.
(grub_pxefs_read): Use block size stored in data->block_size. As the
value of grub_pxe_blksize can be changed after the file is opened.
* fs/i386/pc/pxe.c (curr_file): new variable.
(grub_pxefs_open): Simply the handling of pxe file system. Don't
require the dummy internal file system anymore.
(grub_pxefs_read): Removed.
(grub_pxefs_close): Likewise.
(grub_pxefs_fs_int): Likewise.
(grub_pxefs_read_int): Renamed to grub_pxefs_read. Reinitialize tftp
connection when we switch file.
(grub_pxefs_close_int): Renamed to grub_pxefs_close.
