treewide: use full path to ipm.h header

The build infrastructure should not be adding the drivers subdirectory
to the include path.  Fix the legacy uses that depended on that
addition.

Signed-off-by: Peter Bigot <peter.bigot@nordicsemi.no>

drivers/bluetooth/hci/rpmsg_nrf53.c

@@ -4,7 +4,7 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
-#include <ipm.h>
+#include <drivers/ipm.h>
 
 #include <openamp/open_amp.h>
 #include <metal/sys.h>

drivers/ipm/ipm_nrfx_ipc.c

@@ -5,7 +5,7 @@
  */
 
 #include <string.h>
-#include <ipm.h>
+#include <drivers/ipm.h>
 #include <nrfx_ipc.h>
 #include "ipm_nrfx_ipc.h"
 

drivers/ipm/ipm_stm32_ipcc.c

@@ -7,7 +7,7 @@
 #include <drivers/clock_control.h>
 #include <device.h>
 #include <errno.h>
-#include <ipm.h>
+#include <drivers/ipm.h>
 #include <soc.h>
 
 #include <drivers/clock_control/stm32_clock_control.h>

samples/bluetooth/hci_rpmsg/src/main.c

@@ -14,7 +14,7 @@
 #include <sys/byteorder.h>
 #include <logging/log.h>
 #include <sys/util.h>
-#include <ipm.h>
+#include <drivers/ipm.h>
 
 #include <openamp/open_amp.h>
 #include <metal/sys.h>