KVM: x86: Shove vp_bitmap handling down into sparse_set_to_vcpu_mask()

Move the vp_bitmap "allocation" that's needed to handle mismatched vp_index
values down into sparse_set_to_vcpu_mask() and drop __always_inline from
said helper.  The need for an intermediate vp_bitmap is a detail that's
specific to the sparse translation with mismatched VP<=>vCPU indexes and
does not need to be exposed to the caller.

Regarding the __always_inline, prior to commit f21dd494 ("KVM: x86:
hyperv: optimize sparse VP set processing") the helper, then named
hv_vcpu_in_sparse_set(), was a tiny bit of code that effectively boiled
down to a handful of bit ops.  The __always_inline was understandable, if
not justifiable.  Since the aforementioned change, sparse_set_to_vcpu_mask()
is a chunky 350-450+ bytes of code without KASAN=y, and balloons to 1100+
with KASAN=y.  In other words, it has no business being forcefully inlined.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20211207220926.718794-7-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>