according to the following linux change, BCM2711 uses a different
method for changing pullup/down mode:
abcfd09286 (diff-cf078559c38543ac72c5db99323e236d)
gpiomeminit() was broken, using virtual address for the gpio physseg
instead of the physical one.
cleanup the code, avoid repetition by declaring static u32int *regs
variable. make local variable names consistent.