scripts: Refactor & trim kernel version logic

This is squashed from [1] and [2].

[1]: https://github.com/dakkshesh07/parallax_kernel_realme_rmx1921/commit/453927251afea58cb62f43664306553454a0c0ac
[2]: https://github.com/dakkshesh07/parallax_kernel_realme_rmx1921/commit/1850149495b854d38c5202b0f9b81a2fa9cfa1a2



Co-authored-by: Divyanshu-Modi <divyan.m05@gmail.com>
Co-authored-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Divyanshu-Modi <divyan.m05@gmail.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Cyber Knight <cyberknight755@gmail.com>
Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>