drm/amd/powerplay: suppress compile error around BUG_ON

To suppress the compile error below for "ARCH=arc".
   drivers/gpu/drm/amd/amdgpu/../powerplay/arcturus_ppt.c: In function 'arcturus_fill_eeprom_i2c_req':
>> arch/arc/include/asm/bug.h:22:2: error: implicit declaration of function 'pr_warn'; did you mean 'pci_warn'? [-Werror=implicit-function-declaration]
      22 |  pr_warn("BUG: failure at %s:%d/%s()!\n", __FILE__, __LINE__, __func__); \
         |  ^~~~~~~
   include/asm-generic/bug.h:62:57: note: in expansion of macro 'BUG'
      62 | #define BUG_ON(condition) do { if (unlikely(condition)) BUG(); } while (0)
         |                                                         ^~~
   drivers/gpu/drm/amd/amdgpu/../powerplay/arcturus_ppt.c:2157:2: note: in expansion of macro 'BUG_ON'
    2157 |  BUG_ON(numbytes > MAX_SW_I2C_COMMANDS);

Signed-off-by: Evan Quan <evan.quan@amd.com>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>