treewide: cleanup continuations and remove logging message whitespace

Using C line continuation inside format strings is error prone.
Clean up the unintended whitespace introduced by misuse of \.
Neaten correctly used line continations as well for consistency.

drivers/scsi/arcmsr/arcmsr_hba.c has these errors as well,
but arcmsr needs a lot more work and the driver should likely be
moved to staging instead.

Signed-off-by: Joe Perches <joe@perches.com>
Acked-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>