ShellPkg: acpiview: Remove '/?' from valid command line flags

ShellPkg: acpiview: Remove '/?' from valid command line flags

Acpiview currently allows displaying help info by specifying both
-? and /? flags. This patch removes /? from valid command line
flags that can be passed to the acpiview tool, as this
flag is not used for such purpose in other UEFI shell commands.

Signed-off-by: Krzysztof Koch <krzysztof.koch@arm.com>
Reviewed-by: Alexei Fedorov <Alexei.Fedorov@arm.com>
Reviewed-by: Zhichao Gao <zhichao.gao@intel.com>
Reviewed-by: Sami Mujawar <sami.mujawar@arm.com>