Create new structure NISLANDS_SMC_SWSTATE_SINGLE, as initialState.levels
and ACPIState.levels are never actually used as flexible arrays. Those
arrays can be used as simple objects of type
NISLANDS_SMC_HW_PERFORMANCE_LEVEL, instead.

Currently, the code fails because flexible array _levels_ in
struct NISLANDS_SMC_SWSTATE doesn't allow for code that access
the first element of initialState.levels and ACPIState.levels
arrays:

drivers/gpu/drm/radeon/ni_dpm.c:
1690         table->initialState.levels[0].mclk.vMPLL_AD_FUNC_CNTL =
1691                 cpu_to_be32(ni_pi->clock_registers.mpll_ad_func_cntl);
...
1903:   table->ACPIState.levels[0].mclk.vMPLL_AD_FUNC_CNTL = cpu_to_be32(mpll_ad_func_cntl);
1904:   table->ACPIState.levels[0].mclk.vMPLL_AD_FUNC_CNTL_2 = cpu_to_be32(mpll_ad_func_cntl_2);

because such element cannot exist without previously allocating
any dynamic memory for it (which never actually happens).

That's why struct NISLANDS_SMC_SWSTATE should only be used as type
for object driverState and new struct SISLANDS_SMC_SWSTATE_SINGLE is
created as type for objects initialState, ACPIState and ULVState.

Also, with the change from one-element array to flexible-array member
in commit 434fb1e7 ("drm/radeon/nislands_smc.h: Replace one-element
array with flexible-array member in struct NISLANDS_SMC_SWSTATE"), the
size of dpmLevels in struct NISLANDS_SMC_STATETABLE should be fixed to
be NISLANDS_MAX_SMC_PERFORMANCE_LEVELS_PER_SWSTATE instead of
NISLANDS_MAX_SMC_PERFORMANCE_LEVELS_PER_SWSTATE - 1.

Bug: https://lore.kernel.org/dri-devel/3eedbe78-1fbd-4763-a7f3-ac5665e76a4a@xenosoft.de/
Fixes: 434fb1e7 ("drm/radeon/nislands_smc.h: Replace one-element array with flexible-array member in struct NISLANDS_SMC_SWSTATE")
Cc: stable@vger.kernel.org
Reported-by: Christian Zigotzky <chzigotzky@xenosoft.de>
Tested-by: Christian Zigotzky <chzigotzky@xenosoft.de>
Link: https://lore.kernel.org/dri-devel/9bb5fcbd-daf5-1669-b3e7-b8624b3c36f9@xenosoft.de/Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>