ArmPkg/ArmMmuLib: deobfuscate GetRootTranslationTableInfo ()

ArmPkg/ArmMmuLib: deobfuscate GetRootTranslationTableInfo ()

The relations between T0SZ, the number of translation levels and the
size/alignment of the root table can be expressed in simple arithmetic
expressions, so get rid of the lookup table.

Note that this disregards the fact that the maximum value of T0SZ is
39 not 42 (as one would expect for the smallest VA size using 2 levels)
but since this corresponds to a VA size of 32 MB and 4 MB, respectively,
neither of which are sufficient to run UEFI, we can safely ignore the
distinction.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Leif Lindholm <leif.lindholm@linaro.org>