minix zmap block counts calculation fix

The original minix zmap blocks calculation was correct, in the formula of:

	sbi->s_nzones - sbi->s_firstdatazone + 1

It is

	sp->s_zones - (sp->s_firstdatazone - 1)

in the minix3 source code.

But a later commit 016e8d44 ("fs/minix: Verify bitmap block counts
before mounting") has changed it unfortunately as:

  sbi->s_nzones - (sbi->s_firstdatazone + 1)

This would show free blocks one block less than the real when the total
data blocks are in "full zmap blocks plus one".

This patch corrects that zmap blocks calculation and tidy a printk
message while at it.

Signed-off-by: Qi Yong <qiyong@fc-cn.com>
Cc: Josh Boyer <jwboyer@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>