[PATCH net-next] ptp: don't include ptp_clock_kernel.h in spi.h

[Jakub Kicinski <kuba@kernel.org>]

Commit b42faeee718c ("spi: Add a PTP system timestamp
to the transfer structure") added an include of ptp_clock_kernel.h
to spi.h for struct ptp_system_timestamp but a forward declaration
is enough. Let's use that to limit the number of objects we have
to rebuild every time we touch networking headers.

Tested-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
---
Previous posting: https://lore.kernel.org/all/20210904013140.2377609-1-kuba@kernel.org/
---
 drivers/spi/spi.c       | 1 +
 include/linux/spi/spi.h | 2 +-
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index fdd530b150a7..dc9cf7fc8829 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -33,6 +33,7 @@
 #include <linux/highmem.h>
 #include <linux/idr.h>
 #include <linux/platform_data/x86/apple.h>
+#include <linux/ptp_clock_kernel.h>
 
 #define CREATE_TRACE_POINTS
 #include <trace/events/spi.h>
diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h
index eb7ac8a1e03c..7ab3fed7b804 100644
--- a/include/linux/spi/spi.h
+++ b/include/linux/spi/spi.h
@@ -14,12 +14,12 @@
 #include <linux/completion.h>
 #include <linux/scatterlist.h>
 #include <linux/gpio/consumer.h>
-#include <linux/ptp_clock_kernel.h>
 
 #include <uapi/linux/spi/spi.h>
 
 struct dma_chan;
 struct software_node;
+struct ptp_system_timestamp;
 struct spi_controller;
 struct spi_transfer;
 struct spi_controller_mem_ops;
-- 
2.31.1