SignedCapsulePkg/SystemFirmwareUpdateDxe: Single FMP

SignedCapsulePkg/SystemFirmwareUpdateDxe: Single FMP

https://bugzilla.tianocore.org/show_bug.cgi?id=928

Uninstall all System FMP Protocols for the current FW device.

If an FMP Protocol for the current FW device is already present,
then install the new System FMP protocol onto the same handle as
the FMP Protocol.  Otherwise, install the FMP protocol onto a
new handle.

This supports use cases where multiple capsules for the
same system firmware device are processed on the same
boot of the platform.  It guarantees there is at most one
FMP protocol for each system firmware device.

Cc: Jiewen Yao <jiewen.yao@intel.com>
Signed-off-by: Michael D Kinney <michael.d.kinney@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Reviewed-by: Jiewen Yao <jiewen.yao@intel.com>