webkit: use BR2_ARM_CPU_ARM* options
The webkit package is not available on ARM < v5, so this commit
switches to using the newly introduced BR2_ARM_CPU_ARM* options
instead of per ARM core options.
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>