kernel: add missing config symbol

Signed-off-by: Felix Fietkau <[email protected]>

target/linux/generic/config-4.4

@@ -2854,6 +2854,7 @@ CONFIG_PARTITION_ADVANCED=y
 # CONFIG_PATA_HPT37X is not set
 # CONFIG_PATA_HPT3X2N is not set
 # CONFIG_PATA_HPT3X3 is not set
+# CONFIG_PATA_IMX is not set
 # CONFIG_PATA_ISAPNP is not set
 # CONFIG_PATA_IT8213 is not set
 # CONFIG_PATA_IT821X is not set