On targets that don't have input support enabled in the kernel config,
building kmod-input-touchscreen-ads7846 fails due to a missing
dependency on kmod-input-core. Add the dependency to fix this.
Fixes: 77a54bbf13bf ("kernel: add kmod-input-touchscreen-ads7846")
Reported-by: Hannu Nyman <hannu.nyman@iki.fi>
Signed-off-by: Stijn Tintel <stijn@linux-ipv6.be>