image_types_fsl.bbclass: do not create a partition from 0 to 1MB in i.MX sdcard
The bootrom boots from a fixed 1K offset so we don't need a partition
there and having one makes udev or kernel to probe for it and output
error messages in bootlog:
,----[ boot error messages ]
| ...
| EXT4-fs (mmcblk0p1): VFS: Can't find ext4 filesystem
| EXT3-fs (mmcblk0p1): error: can't find ext3 filesystem on dev mmcblk0p1.
| EXT2-fs (mmcblk0p1): error: can't find an ext2 filesystem on dev mmcblk0p1.
| FAT: bogus number of reserved sectors
| VFS: Can't find a valid FAT filesystem on dev mmcblk0p1.
| cramfs: wrong magic
| FAT: bogus number of reserved sectors
| VFS: Can't find a valid FAT filesystem on dev mmcblk0p1.
| ...
`----
Signed-off-by: Otavio Salvador <otavio@ossystems.com.br>