panvk: Enable VK_KHR_vertex_attribute_divisor

What does this MR do and why?

panvk: Enable VK_KHR_vertex_attribute_divisor
    
Panvk currently enables VK_EXT_vertex_attribute_divisor, but Mali HW
does not support a non-zero firstInstance when a divisor is used.
supportsNonZeroFirstInstance is correctly set to false to advertise
this, however this property was only added when the extension was
promoted. Thus we need to remove support for
VK_EXT_vertex_attribute_divisor and enable
VK_KHR_vertex_attribute_divisor instead.
    
Also fixes an issue with non-zero divisor for v10.

There seems to be a bug in CTS where tests for vertexAttributeInstanceRateZeroDivisor are not run when only the EXT extension is supported.

Fixes dEQP-VK.*vertex_attribute_divisor.*non_zero.*