OvmfPkg/BlockMmioToBlockIoDxe: list "BlockIo.h" in the INF file

OvmfPkg/BlockMmioToBlockIoDxe: list "BlockIo.h" in the INF file

Among other things, the header file declares the
"gBlockMmioToBlockIoComponentName" and "gBlockMmioToBlockIoComponentName2"
protocol instance structures. They are defined and initialized in
"ComponentName.c" and installed in "BlockIo.c".

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>