MdeModulePkg/PartitionDxe: Initialize the array after declaration
MdeModulePkg/PartitionDxe: 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 <fa9eeec52367040ac98013bc4b2913db170588f8@intel.com>
Cc: Paulo Alcantara <875cae76f32e6d68a7dda9c640ac11e815398b68@zytor.com>
Cc: Ruiyu Ni <9fa3a6894a36bca79e6a72ad65af5a5702efecd1@intel.com>
Cc: Star Zeng <5c6bb72efe464613af94e84c05522a361b23844a@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Dandan Bi <1e8692d8ed8470b17e8ddd7612a0f029768dcb56@intel.com>
Reviewed-by: Paulo Alcantara <875cae76f32e6d68a7dda9c640ac11e815398b68@zytor.com>
Reviewed-by: Star Zeng <5c6bb72efe464613af94e84c05522a361b23844a@intel.com>

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