kfifo: don't include dma-mapping.h in kfifo.h

kfifo: don't include dma-mapping.h in kfifo.h

Nothing in kfifo.h directly needs dma-mapping.h, only two macros
use DMA_MAPPING_ERROR when actually instantiated.  Drop the
dma-mapping.h include to reduce include bloat.

Add an explicity <linux/io.h> include to drivers/mailbox/omap-mailbox.c
as that file uses __raw_readl and __raw_writel through a complicated
include chain involving <linux/dma-mapping.h>

Fixes: d52b761e4b1a ("kfifo: add kfifo_dma_out_prepare_mapped()")
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20241023055317.313234-1-hch@lst.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>