Nt32Pkg/Nt32Pkg.fdf: Increase the size of FLASH Device.

Nt32Pkg/Nt32Pkg.fdf: Increase the size of FLASH Device.

Currently, the FV image size is not enough for the modules after
we enable some flags defined in Nt32Pkg.dsc, e.g:
 DEFINE SECURE_BOOT_ENABLE      = TRUE
 DEFINE TLS_ENABLE              = TRUE
 DEFINE NETWORK_IP6_ENABLE      = TRUE

This patch is to increase the size of FLASH Device to meet the requirement.

Cc: Ruiyu Ni <ruiyu.ni@intel.com>
Cc: Hao Wu <hao.a.wu@intel.com>
Cc: Ye Ting <ting.ye@intel.com>
Cc: Fu Siyuan <siyuan.fu@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Wu Jiaxin <jiaxin.wu@intel.com>
Reviewed-by: Hao Wu <hao.a.wu@intel.com>