ARM: orion: only select I2C_BOARDINFO when using I2C

If we select I2C_BOARDINFO and I2C is disabled, we get a
harmless Kconfig warning:

warning: (MACH_DOVE_DB && MACH_DB88F5281 && MACH_RD88F5182 && MACH_RD88F5182_DT && MACH_KUROBOX_PRO && MACH_DNS323 && MACH_LINKSTATION_PRO && MACH_LINKSTATION_LSCHL && MACH_LINKSTATION_LS_HGL && MACH_NET2BIG) selects I2C_BOARDINFO which has unmet direct dependencies (I2C)

Making the select itself conditional avoids the warning and
makes the kernel slightly smaller as the compiler will be
able to drop the unused board info.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Acked-by: Jason Cooper <jason@lakedaemon.net>
Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>