Update android.mk to support custom mkbootimg command

[Gustavo2Toledo]

This commit modifies the android.mk file to resolve issues with building the halium-boot.img by updating the mkbootimg command. The changes include:

• Adding support for custom kernel command-line arguments.
• Handling the creation of the boot image with custom ramdisk and kernel parameters.
• Ensuring that the correct fstab files are detected and used for partition information.
• Modifying how the initramfs is fetched or used, allowing for better customization for different devices.

This update ensures more flexibility when creating halium-boot.img and improves compatibility with various devices and configurations, based on the updated kernel and partition setups.