ArmPlatformPkg/BootMenu.c: Print loader type in a more friendly way.

ArmPlatformPkg/BootMenu.c: Print loader type in a more friendly way.

In debug mode, the loader type (EFI application or linux kernel with
FDT/ATAG support) is displayed in UEFI boot menu.

Before this patch it was printed as a decimal number which is
meaningful to the user only if he knows the values of the
ARM_BDS_LOADER_TYPE enumeration type in the source code...

This patch modifies the boot menu so that it also prints a
user-friendly string describing the loader type.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Olivier Martin <olivier.martin@arm.com>
git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@14175 6f19259b-4bc3-4df7-8a09-765794883524