ArmVirtPkg/ArmPlatformLibQemu: Make IdMap.S BTI compatible
The IdMap.S asm source file has not executable content, but its lack of
a BTI annotation prevents the linker from marking any executables it
emits as BTI compatible if this object is part of the build. So add the
BTI note by hand.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>