iio: accel: bma220: cleanup includes

Tweak includes based on requirements.

Signed-off-by: Petre Rodan <petre.rodan@subdimension.ro>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com> #added linux/errno.h

drivers/iio/accel/bma220_spi.c

@@ -6,9 +6,11 @@
  */
 
 #include <linux/bits.h>
-#include <linux/kernel.h>
+#include <linux/errno.h>
 #include <linux/mod_devicetable.h>
 #include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/pm.h>
 #include <linux/types.h>
 #include <linux/spi/spi.h>