[HVM][SVM] Do not delay ExtInt event injection if RFLAGS.IF==0.

[HVM][SVM] Do not delay ExtInt event injection if RFLAGS.IF==0.

AMD-V does not require the delaying of interrupt injection if the guest
IF_FLAG disallows interrupts.  Remove the code in svm_intr_assist()
that was checking the guest IF in eflags.

This patch fixes the problem with HVM Windows guests, with observing a
very slow timer countdown on the initial boot menu, when there is more
than one boot option.  Kbd response in this same Windows boot menu is
also acceptably responsive with this patch.

Signed-off-by: Tom Woller <thomas.woller@amd.com>=20