1.Add code to check the pointer 'CorrectedPath' in Ls.c line 460 before referenced...

 1.Add code to check the pointer  'CorrectedPath' in Ls.c line 460 before referenced. 2.Not use  explicit comparisons to TRUE or FALSE for Boolean variable in Ls.c. 3.Add doxygen tags in comment and return type for 'ToLower' in ShellProtocol.c.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Shumin Qiu <shumin.qiu@intel.com>
Reviewed-by: Jaben Carsey <Jaben.carsey@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@15320 6f19259b-4bc3-4df7-8a09-765794883524