HSI: cmt_speech: fix timestamp interface

The user interface for timestamps in the new cmt_speech
driver is broken in multiple ways:

- The layout is incompatible between 32-bit and 64-bit user
  space, because of the size differences in 'struct timespec'.
  This means that the driver can not work when used with 32-bit
  user space on a 64-bit kernel.

- As there are plans to change 32-bit user space to use
  a 64-bit time_t type in the future, it will also be
  incompatible with new 32-bit user space.

- It is using ktime_get_ts under it's deprecated alias
  (do_posix_clock_monotonic_gettime).

To keep support for the user space tools written for this driver (which
have lived many years out-of-tree), the interface has been hardened to
unsigned 32-bit values.

Reported-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Sebastian Reichel <sre@kernel.org>

include/uapi/linux/hsi/cs-protocol.h

@@ -75,6 +75,15 @@ struct cs_buffer_config {
 	__u32 reserved[4];
 };
 
+/*
+ * struct for monotonic timestamp taken when the
+ * last control command was received
+ */
+struct cs_timestamp {
+	__u32 tv_sec;  /* seconds */
+	__u32 tv_nsec; /* nanoseconds */
+};
+
 /*
  * Struct describing the layout and contents of the driver mmap area.
  * This information is meant as read-only information for the application.
@@ -91,11 +100,8 @@ struct cs_mmap_config_block {
 	__u32 rx_ptr;
 	__u32 rx_ptr_boundary;
 	__u32 reserved3[2];
-	/*
-	 * if enabled with CS_FEAT_TSTAMP_RX_CTRL, monotonic
-	 * timestamp taken when the last control command was received
-	 */
-	struct timespec tstamp_rx_ctrl;
+	/* enabled with CS_FEAT_TSTAMP_RX_CTRL */
+	struct cs_timestamp tstamp_rx_ctrl;
 };
 
 #define CS_IO_MAGIC		'C'