MdeModulePkg/UdfDxe: Initialize the array after declaration

MdeModulePkg/UdfDxe: Initialize the array after declaration

Initialize the array DescriptorLBAs[] after declaration to fix
non-constant aggregate initializer warning in VS tool chains.

Cc: Eric Dong <eric.dong@intel.com>
Cc: Paulo Alcantara <pcacjr@zytor.com>
Cc: Ruiyu Ni <ruiyu.ni@intel.com>
Cc: Star Zeng <star.zeng@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Dandan Bi <dandan.bi@intel.com>
Reviewed-by: Paulo Alcantara <pcacjr@zytor.com>
Reviewed-by: Star Zeng <star.zeng@intel.com>