layers: LX249, Remove MSAA coherency checks from BeginRenderPass
layers: LX249, Remove MSAA coherency checks from BeginRenderPass

Don't see any language in the spec saying that sample counts need to be valid at
RP begin time. A PSO with matching MSAA state can be bound after the RP is
started.

KhronosGroup/Vulkan-Tools,KhronosGroup/Vulkan-Tools,KhronosGroup/Vulkan-Tools,KhronosGroup/Vulkan-Tools