ymodem: fix examples due to new API
romfs: check the dirent before use it

System will crash when the romfs is erased. Add checks before using them
to avoid it.
romfs: rewrite mkromfs.py
Merge pull request #368 from grissiom/romfs-next

Romfs next
Merge pull request #367 from grissiom/ymodem-fix

ymodem: fix examples due to new API
Merge pull request #369 from BernardXiong/master

[BSP] Add GCC compiler support for mb9bf568r
romfs: fix a use-before-set bug on checking the dirent
bsp:fix the bug of lpc43xx uart interrupt enable in driver initialize.
Merge pull request #370 from grissiom/romfs-next

romfs: fix a use-before-set bug on checking the dirent
Merge pull request #371 from nongxiaoming/master

bsp:fix the bug of lpc43xx uart interrupt enable in driver initialize.
modified the comments of block device geometry structure, to tell everyone the unit of block_size is byte.
update the change logs
Merge pull request #372 from pangweishen/master

update the change logs