linux-fslc-imx: upgrade to rel_imx_5.4.70_2.3.0 from NXP
Kernel repository has a new branch introduced, which is based on NXP
release 5.4.70-2.3.0 and has latest stable patchlevel applied to it.
Current version of up-merged kernel is 5.4.92.
Update kernel recipe to include new kernel version and align kernel
config files based on following NXP configurations:
- imx_v8_defconfig used for i.MX8 family
- i.MX6/7 families kernel config file did not require any additional sync,
it matches to the imx_v7_defconfig
Tracking information in recipe is updated to include new branch, tag and
cherry-picks from NXP branch, together with patches applied from various
sources.
