When CONFIG_OF is disabled then the matching table is not referenced and
the following warning appears:

drivers/clk/ralink/clk-mtmips.c:821:34: warning: unused variable 'mtmips_of_match' [-Wunused-const-variable]
821 |   static const struct of_device_id mtmips_of_match[] = {
    |                          ^

There are two match tables in the driver: one for the clock driver and the
other for the reset driver. The only difference between them is that the
clock driver uses 'data' and does not have 'ralink,rt2880-reset' compatible.
Both just can be merged into a single one just by adding the compatible
'ralink,rt2880-reset' entry to 'mtmips_of_match[]', which will allow it to
be used for 'mtmips_clk_driver' (which doesn't use the data) as well as for
'mtmips_clk_init()' (which doesn't need get called for 'ralink,rt2880-reset').

Doing in this way ensures that 'CONFIG_OF' is not disabled anymore so the
above warning disapears.

Fixes: 6f3b1558 ("clk: ralink: add clock and reset driver for MTMIPS SoCs")
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202307242310.CdOnd2py-lkp@intel.com/Suggested-by: Arnd Bergmann <arnd@kernel.org>
Signed-off-by: Sergio Paracuellos <sergio.paracuellos@gmail.com>
Link: https://lore.kernel.org/r/20230827023932.501102-1-sergio.paracuellos@gmail.comReviewed-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>