serial: ifx6x60: different SPI word width configure requires different swap process

SPI protocol driver only provide one function (swap_buf()) to swap SPI
data into big endian format, which is only available when SPI
controller's word width is 16 bits. But word width could be configured
as 8/16/32 bits, different word width configure should be mapped to
different swap methods.This patch is to make SPI protocol driver choose
the right swap function corresponding to SPI word width configuration.

cc: liu chuansheng <chuansheng.liu@intel.com>
cc: Chen Jun <jun.d.chen@intel.com>
Signed-off-by: channing <chao.bi@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/tty/serial/ifx6x60.h b/drivers/tty/serial/ifx6x60.h
index e8464ba..d8869f5 100644
--- a/drivers/tty/serial/ifx6x60.h
+++ b/drivers/tty/serial/ifx6x60.h
@@ -124,6 +124,7 @@
 #define MR_INPROGRESS	1
 #define MR_COMPLETE	2
 	wait_queue_head_t mdm_reset_wait;
+	void (*swap_buf)(unsigned char *buf, int len, void *end);
 };
 
 #endif /* _IFX6X60_H */