udeb: add intel_lpss* (optional) to kernel-image (Closes: #1032136)

Many laptops have their touchpad accessible over I2C, only visible if LPSS is available in the installer.

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I wasn't sure entirely how to best request this inclusion:

• While my primary concern is I2C for touchpads, LPSS can give access to other peripherals, including serial ones. So it wasn't clear to me we should ship LPSS modules in i2c-modules, since they might be useful for serial-modules as well… In the end, kernel-image looked best.
• Since LPSS-related options are set via kernelarch-x86, it might make sense to list these modules in amd64 and i386 files, but given there are no arch-specific files at the moment, I want for the generic kernel-image file, with the ? specifier.
• My initial attempt was intel_lpss* ? but that didn't select anything, hence my listing all modules explicitly.