net/atm/common.c: checkpatch cleanups

Convert #include <asm... to #include <linux...
Move EXPORT_SYMBOL
Spacing cleanups
Use __func__ in printks
Indent switch/case statements
Move trailing statements to new line
Hoist assigns from if tests

Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: David S. Miller <davem@davemloft.net>