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>