include/linux/printk.h: move console functions and variables together

There are many uses of printk_once(KERN_<level>, so add pr_<level>_once
macros to avoid printk_once(KERN_<level> pr_fmt(fmt).

Add an #ifdef CONFIG_PRINTK for print_hex_dump and static inline void
functions for the #else cases to reduce embedded code size.  Neaten and
organize the rest of the code.

This patch:

Move console functions and variables together.

Signed-off-by: Joe Perches <joe@perches.com>
Cc: Matt Mackall <mpm@selenic.com>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>