ubi: fastmap: Add fastmap control support for Module parameters

hulk inclusion
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I5WQRM


CVE: NA

--------------------------------

This patch add 'enable_fm' as 5th module init parameters to control
fastmap  enable or not. When the value is 0, fastmap will not create
and existed fastmap will destroyed for the given ubi device. Default
value is 0.

To enable or disable fastmap during module loading, fm_autoconvert
must be set to non-zero.

+-----------------+---------------+---------------------------+
|        \        |  enable_fm=0  |  enable_fm=1              |
+-----------------+---------------+---------------------------+
|fm_autoconvert=Y |  disable fm   |  enable fm                |
+---------------------------------+---------------------------+
|fm_autoconvert=N |  disable fm   | Enable fastmap. If fastmap|
|                 |               | exists in the old image,  |
+------------------------------------------------------------ +

Example:
  # - Attach mtd1 to ubi1, disable fastmap, mtd2 to ubi2, enable
      fastmap.
  # modprobe ubi mtd=1,0,0,1,0 mtd=2,0,0,2,1 fm_autoconvert=1

  # - If 5th parameter is not specified, the value is 0, fastmap is
      disable
  # modprobe ubi mtd=1 fm_autoconvert=1

Signed-off-by: ZhaoLong Wang <wangzhaolong1@huawei.com>
Reviewed-by: Zhihao Cheng <chengzhihao1@huawei.com>
Reviewed-by: Zhang Yi <yi.zhang@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>