[SCSI] ses: fix data corruption

one system: initrd get courrupted:

RAMDISK: Compressed image found at block 0
RAMDISK: incomplete write (-28 != 2048) 134217728
crc error
VFS: Mounted root (ext2 filesystem).
Freeing unused kernel memory: 388k freed
init_special_inode: bogus i_mode (177777)
Warning: unable to open an initial console.
init_special_inode: bogus i_mode (177777)
init_special_inode: bogus i_mode (177777)
Kernel panic - not syncing: No init found.  Try passing init= option to kernel.

bisected to
commit 9927c688
Author: James Bottomley <James.Bottomley@HansenPartnership.com>
Date:   Sun Feb 3 15:48:56 2008 -0600

    [SCSI] ses: add new Enclosure ULD

changes:
1. change char to unsigned char to avoid type change later.
2. preserve len for page1
3. need to move desc_ptr even the entry is not enclosure_component_device/raid.
   so keep desc_ptr on right position
4. record page7 len, and double check if desc_ptr out of boundary before touch.
5. fix typo in subenclosure checking: should use hdr_buf instead.

[jejb: style fixes]

Signed-off-by: Yinghai Lu <yinghai.lu@sun.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>