4MB flash size as build default.

[Prerna <saxenap.ltc@gmail.com>]

Hi Laszlo,
I noticed that the following commit was used to make the 4MB flash layout
the default for edk2 builds briefly:

bba8dfbec3bb OvmfPkg: make the 4MB flash size the default

However, it was later reverted :

6e49d01cfb43 Revert "OvmfPkg: make the 4MB flash size the default"

presumably to fix this issue:

0c79471d6a98 OvmfPkg/PlatformPei: handle non-power-of-two spare
                  size for emu variables

Given that the above commit was also merged, why does edk2 still default to
the 2MB flash layout for builds? Do you see any other issues too with the
4MB flash layout ?

Regards,
Prerna