kbuild: clean up modpost.c

akpm complained about overly long lines in modpost.c and
when started additional style issues were fixed:

o Updated my copyright
o Removed unneeded {}
o Drop assignments in if ()
o Spaces around operators
o Break long lines
o locate * near variable not type
o Fix a format specifier for sizeof()
o Corrected placement of '{' and '}'
o spaces to tabs (but use tabs only for indention)

modpost.c is not checkpatch clean. Readability were favoured
on top of checkpatch compliance.
But checkpatch were used to find additional stuff to clean up.
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>