boot/edk2: refine license

The edk2 project is licensed under the BSD-2-Clause license with a patent
grant, as per commit 304bff7223a8 ("edk2: Change License.txt from 2-Clause
BSD to BSD+Patent").

There is a BSD-2-Clause-Patent SPDX license identifier[1] for this case,
therefore refine the edk2 package to use this more specific identifier.

[1]: https://spdx.org/licenses/BSD-2-Clause-Patent.html

Signed-off-by: Vincent Stehlé <vincent.stehle@arm.com>
Cc: Dick Olsson <hi@senzilla.io>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

boot/edk2/edk2.mk

@@ -7,7 +7,7 @@
 EDK2_VERSION = edk2-stable202102
 EDK2_SITE = https://github.com/tianocore/edk2
 EDK2_SITE_METHOD = git
-EDK2_LICENSE = BSD-2-Clause
+EDK2_LICENSE = BSD-2-Clause-Patent
 EDK2_LICENSE_FILES = License.txt
 EDK2_CPE_ID_VENDOR = tianocore
 EDK2_DEPENDENCIES = edk2-platforms host-python3 host-acpica host-util-linux