drm/amdkfd: Change svm_range_get_info return type

drm/amdkfd: Change svm_range_get_info return type

Static analysis shows that pointer "svms" cannot be NULL because it points
to the object "struct svm_range_list". Remove the extra NULL check. It is
meaningless and harms the readability of the code.

In the function svm_range_get_info() there is no possibility of failure.
Therefore, the caller of the function svm_range_get_info() does not need
a return value. Change the function svm_range_get_info() return type from
"int" to "void".

Since the function svm_range_get_info() has a return type of "void". The
caller of the function svm_range_get_info() does not need a return value.
Delete extra code.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Signed-off-by: Andrey Vatoropin <a.vatoropin@crpt.ru>
Signed-off-by: Felix Kuehling <felix.kuehling@amd.com>
Reviewed-by: Felix Kuehling <felix.kuehling@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>