ar7: remove 2.6.37 support

target/linux/ar7/config-2.6.37

target/linux/ar7/patches-2.6.37/100-titan-gpio-size.patch

target/linux/ar7/patches-2.6.37/110-flash.patch

target/linux/ar7/patches-2.6.37/120-gpio_chrdev.patch

...linux/ar7/patches-2.6.37/160-vlynq_try_remote_first.patch

target/linux/ar7/patches-2.6.37/500-serial_kludge.patch

target/linux/ar7/patches-2.6.37/920-ar7part.patch

target/linux/ar7/patches-2.6.37/950-cpmac_titan.patch

target/linux/ar7/patches-2.6.37/972-cpmac_fixup.patch

.../linux/ar7/patches-2.6.37/973-cpmac_handle_mvswitch.patch

target/linux/ar7/patches-2.6.37/999-gt701_leds.patch