x86/vdso/kbuild: Group non-standard build attributes and primary object file rules together

The fresh changes to the vDSO Makefile in:

  289d0a47 ("x86/vdso: Use CONFIG_COMPAT_32 to specify vdso32")
  329b77b5 ("x86/vdso: Simplify obj-y addition")

Conflicted with a pending change in:

  b388e57d ("x86/vdso: Fix rethunk patching for vdso-image-{32,64}.o")

Which was resolved in a simple fasion in this merge commit:

  f14df823 ("Merge branch 'x86/vdso' into x86/core, to resolve conflict and to prepare for dependent changes")

... but all these changes make me look and notice a bit of historic baggage
left in the Makefile:

  - Disordered build rules where non-standard build attributes relating to
    were placed sometimes several lines after - and sometimes *before*
    the .o build rules of the object files... Functional but inconsistent.

  - Inconsistent vertical spacing, stray whitespaces, inconsistent spelling
    of 'vDSO' over the years, a few spelling mistakes and inconsistent
    capitalization of comment blocks.

Tidy it all up. No functional changes intended.

Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Borislav Petkov (AMD) <bp@alien8.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>