ShellPkg: Fix unhandled value in switch statement

ShellPkg: Fix unhandled value in switch statement

This patch fixes the following compile error under GCC 5.3.1:

/home/pcacjr/work/edk2.git/ShellPkg/Application/Shell/ShellManParser.c:
In function 'IsTitleHeader':
/home/pcacjr/work/edk2.git/ShellPkg/Application/Shell/ShellManParser.c:502:5:
error: enumeration value 'Final' not handled in switch [-Werror=switch]
     switch (State) {
     ^

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Paulo Alcantara <paulo.alc.cavalcanti@hp.com>
Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Jaben Carsey <jaben.carsey@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@19304 6f19259b-4bc3-4df7-8a09-765794883524