include/linux/memblock.h: Clean up code for several trivial details

Correct the function parameters alignment, since original code already
use both tabs and white spaces together for the incorrect parameters
alignment functions.

If one line can hold one statement within 80 columns, let it in one line
(original code did not consider about the tabs/spaces for 2nd line when
a statement is separated into 2 lines).

Try to let '' aligned within one macro, since all related lines are
short enough.

Remove useless statement "idx = 0;", and always assign rgn within the
'for' statement.

Link: http://lkml.kernel.org/r/1464904899-1714-1-git-send-email-chengang@emindsoft.com.cn


Signed-off-by: Chen Gang <gang.chen.5i5j@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>