switch CONFIG_I2C to =m by default on avr32 (see #3756)

SVN-Revision: 12037

target/linux/avr32/config-default

@@ -55,7 +55,7 @@ CONFIG_HAVE_KPROBES=y
 # CONFIG_HAVE_KRETPROBES is not set
 CONFIG_HAVE_OPROFILE=y
 # CONFIG_HW_RANDOM is not set
-CONFIG_I2C=y
+CONFIG_I2C=m
 # CONFIG_I2C_ALGOBIT is not set
 # CONFIG_I2C_ATMELTWI is not set
 CONFIG_I2C_BOARDINFO=y