drm/amdgpu: Fix uninitalized variable in kgd2kfd_device_init

drivers/gpu/drm/amd/amdgpu/../amdkfd/kfd_device.c:613:4: error: variable 'num_xcd' is uninitialized when used here [-Werror,-Wuninitialized]
                        num_xcd, kfd->adev->gfx.num_xcc_per_xcp);
                        ^~~~~~~
include/linux/dev_printk.h:144:65: note: expanded from macro 'dev_err'
        dev_printk_index_wrap(_dev_err, KERN_ERR, dev, dev_fmt(fmt), ##__VA_ARGS__)
                                                                       ^~~~~~~~~~~
include/linux/dev_printk.h:110:23: note: expanded from macro 'dev_printk_index_wrap'
                _p_func(dev, fmt, ##__VA_ARGS__);                       \
                                    ^~~~~~~~~~~
drivers/gpu/drm/amd/amdgpu/../amdkfd/kfd_device.c:597:13: note: initialize the variable 'num_xcd' to silence this warning
        int num_xcd, partition_mode;
                   ^
                    = 0
1 error generated.

Cc: Luben Tuikov <luben.tuikov@amd.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: Christian König <christian.koenig@amd.com>
Cc: Felix Kuehling <Felix.Kuehling@amd.com>
Cc: Mukul Joshi <mukul.joshi@amd.com>
Signed-off-by: Srinivasan Shanmugam <srinivasan.shanmugam@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>