samsung-n5110: backport getrandom syscall #107

This backports the getrandom syscall based on the backports found in the LineageOS kernel android_kernel_sony_apq8064 from 3.4. Note that the syscall is not wired up on x86 - but this is irrelevant for this device anyway. To get proper random numbers, probably further changes for support for prandom_reseed_late and periodic reseeding should be backported. However, these changes are quite incompatible with 3.0 as the affected functions were renamed between 3.0 and 3.4. Backporting the renaming and then also the other should be possible, but I have not tried it yet. While the renaming affects a lot of files the changes are very simple and should thus be easy to re-apply on the older version. Then applying the other patches should be way easier. I would be happy with merging this as is as a starting point as without this the device is basically unusable.