ARM: uniphier: display revision of Micro Support Card 3.6.x kindly

ARM: uniphier: display revision of Micro Support Card 3.6.x kindly

The revision of the original support card (rev 3.5, rev 3.6) fits in
the 8 bit width revision register.  When it was extended in a weird
way, it was versioned in the format of "3.6.x" (where it should have
been "3.7", of course).  What is worse, only the sub-level version
"6.x" was recorded in the 8 bit width register, completely ignoring
the compatibility of the revision register format.

This patch saves madly-versioned support cards by assuming the major
version "3" when the MSB 4 bit of the register is read as "6".  With
this, the support card revision that were displayed as "6.10" is now
corrected to "3.6.10".

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>