ShellPkg/UefiShellDebug1: Lower indentation level in MainCmdXXX() (1/4)

This patch aims to help breaking down the long functions present in
the ShellPkg and reduce complexity/nested code and conditions.

Lower the indentation level in the newly created MainCmdXXX()
functions.

To avoid having one large commit updating all the UefiShellDebug1
commands, only update these files:
- Comp.c
- Cxl.c
- Dblk.c
- Dmem.c
- DmpStore.c

No functional change should be induced by this patch.

Signed-off-by: Pierre Gondois <pierre.gondois@arm.com>