drm/amdgpu: Update min() to min_t() in 'amdgpu_info_ioctl'

Fixes the following:

WARNING: min() should probably be min_t(size_t, size, sizeof(ip))
+               ret = copy_to_user(out, &ip, min((size_t)size, sizeof(ip)));

And other style fixes:

WARNING: Prefer 'unsigned int' to bare use of 'unsigned'
WARNING: Missing a blank line after declarations

Cc: Christian König <christian.koenig@amd.com>
Cc: Alex Deucher <alexander.deucher@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>