KVM: VMX: Invert the inlining of MSR interception helpers

Invert the inline declarations of the MSR interception helpers between
the wrapper, vmx_set_intercept_for_msr(), and the core implementations,
vmx_{dis,en}able_intercept_for_msr().  Letting the compiler _not_
inline the implementation reduces KVM's code footprint by ~3k bytes.

Back when the helpers were added in commit 904e14fb ("KVM: VMX: make
MSR bitmaps per-VCPU"), both the wrapper and the implementations were
__always_inline because the end code distilled down to a few conditionals
and a bit operation.  Today, the implementations involve a variety of
checks and bit ops in order to support userspace MSR filtering.

Furthermore, the vast majority of calls to manipulate MSR interception
are not performance sensitive, e.g. vCPU creation and x2APIC toggling.
On the other hand, the one path that is performance sensitive, dynamic
LBR passthrough, uses the wrappers, i.e. is largely untouched by
inverting the inlining.

In short, forcing the low level MSR interception code to be inlined no
longer makes sense.

No functional change intended.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210423221912.3857243-1-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>