i2c: Remove unused Netlogic/Sigma Designs XLR driver

Commits 95b8a5e0 ("MIPS: Remove NETLOGIC support") and edd4488a
("ARM: remove tango platform") removed Netlogic XLR and Sigma Designs
Tango platforms which means there are no platforms using the XLR I2C
driver and it can be removed.

Signed-off-by: Rob Herring <robh@kernel.org>
Signed-off-by: Wolfram Sang <wsa@kernel.org>