OvmfPkg/AcpiTimerLib: list "AcpiTimerLib.h" in the INF files

OvmfPkg/AcpiTimerLib: list "AcpiTimerLib.h" in the INF files

The header file declares the InternalAcpiGetTimerTick() function. The
function is called from "AcpiTimerLib.c", which is built into all three
library instances. The function is defined individually per library
instance, in "BaseRomAcpiTimerLib.c", "BaseAcpiTimerLib.c", and
"DxeAcpiTimerLib.c" (enumerated in increasing firmware phase order).

Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Suggested-by: Michael Kinney <michael.d.kinney@intel.com>
Ref: http://mid.mail-archive.com/E92EE9817A31E24EB0585FDF735412F56327F7D3@ORSMSX113.amr.corp.intel.com
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>