OvmfPkg: raise DXEFV size to 13 MB in the traditional platform FDFs

OvmfPkg: raise DXEFV size to 13 MB in the traditional platform FDFs

Similarly to the "cadence" mentioned in commit d272449d9e1e ("OvmfPkg:
raise DXEFV size to 11 MB", 2018-05-29), it's been ~1.75 years since
commit 5e75c4d1fe4f ("OvmfPkg: raise DXEFV size to 12 MB", 2020-03-11),
and we've outgrown DXEFV again (with NOOPT builds).  Increase the DXEFV
size to 13MB now.

Do not modify all platform FDF files under OvmfPkg.  "BhyveX64.fdf" is
still at 11MB, "OvmfXen.fdf" at 10MB.  The "AmdSevX64.fdf",
"CloudHvX64.fdf", "IntelTdxX64.fdf" and "MicrovmX64.fdf" flash devices
could be modified similarly (from 12MB to 13MB), but I don't use or build
those platforms.

Tested on:
- IA32, q35, SMM_REQUIRE, Fedora 30 guest
- X64, pc (i440fx), no SMM, RHEL-7.9 guest
- IA32X64, q35, SMM_REQUIRE, RHEL-7.9 guest

Test steps:
- configure 3 VCPUs
- boot
- run "taskset -c $I efibootmgr" with $I covering 0..2
- systemctl suspend
- resume from virt-manager
- run "taskset -c $I efibootmgr" with $I covering 0..2

Cc: Anthony Perard <anthony.perard@citrix.com>
Cc: Ard Biesheuvel <ardb+tianocore@kernel.org>
Cc: Brijesh Singh <brijesh.singh@amd.com>
Cc: Erdem Aktas <erdemaktas@google.com>
Cc: Gerd Hoffmann <kraxel@redhat.com>
Cc: James Bottomley <jejb@linux.ibm.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Julien Grall <julien@xen.org>
Cc: Min Xu <min.m.xu@intel.com>
Cc: Peter Grehan <grehan@freebsd.org>
Cc: Rebecca Cran <rebecca@bsdio.com>
Cc: Sebastien Boeuf <sebastien.boeuf@intel.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=4236
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>