i2c-tools: include LGPL-2.1+ license for libi2c

Extend i2c-tools SPDX identifiers to include the library license.
Also include COPYING.LGPL and README to license files.

The ic2-tools readme states:

LICENSE

Check the documentation of individual tools for licensing information.
The library is released under the LGPL version 2.1 or later, while most
tools are released under the GPL version 2 or later, but there are a few
exceptions.

Signed-off-by: Brad Love <brad@nextdimension.cc>
[Thomas: add hashes for COPYING.LGPL and README.]
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

package/i2c-tools/i2c-tools.hash

@@ -1,5 +1,7 @@
 # Locally computed
 sha256 d900ca1c11c51ea20caa50b096f948008b8a7ad832311b23353e21baa7af28d6  i2c-tools-4.0.tar.xz
 
-# License file
+# License files
 sha256 ab15fd526bd8dd18a9e77ebc139656bf4d33e97fc7238cd11bf60e2b9b8666c6  COPYING
+sha256 dc626520dcd53a22f727af3ee42c770e56c97a64fe3adb063799d8ab032fe551  COPYING.LGPL
+sha256 158abc6886c2c6e2dec7e9cb11b46fd41cb13a015c5057c2a587ef581f9142f8  README

package/i2c-tools/i2c-tools.mk

@@ -7,8 +7,8 @@
 I2C_TOOLS_VERSION = 4.0
 I2C_TOOLS_SOURCE = i2c-tools-$(I2C_TOOLS_VERSION).tar.xz
 I2C_TOOLS_SITE = https://www.kernel.org/pub/software/utils/i2c-tools
-I2C_TOOLS_LICENSE = GPL-2.0+, GPL-2.0 (py-smbus)
-I2C_TOOLS_LICENSE_FILES = COPYING
+I2C_TOOLS_LICENSE = GPL-2.0+, GPL-2.0 (py-smbus), LGPL-2.1+ (libi2c)
+I2C_TOOLS_LICENSE_FILES = COPYING COPYING.LGPL README
 I2C_TOOLS_MAKE_OPTS = EXTRA=eeprog
 
 ifeq ($(BR2_PACKAGE_PYTHON),y)