hvf: correctly inject VMCS_INTR_T_HWINTR versus VMCS_INTR_T_SWINTR.

hvf: correctly inject VMCS_INTR_T_HWINTR versus VMCS_INTR_T_SWINTR.

Previous implementation in hvf_inject_interrupts() would always inject
VMCS_INTR_T_SWINTR even when VMCS_INTR_T_HWINTR was required.  Now
correctly determine when VMCS_INTR_T_HWINTR is appropriate versus
VMCS_INTR_T_SWINTR.

Make sure to clear ins_len and has_error_code when ins_len isn't
valid and error_code isn't set.

Signed-off-by: Cameron Esfahani <dirty@apple.com>
Message-Id: <bf8d945ea1b423786d7802bbcf769517d1fd01f8.1575330463.git.dirty@apple.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>