tegra3-common: Use legacy mmap

From the corresponding bionic commit:

* Pre-lollipop mmap would not care whether offset was signed
  or unsigned.
* Lollipop adds 64-bit support which results in sign extension
  of offset, causing a negative offset when
  a positive offset > 2^31 is given.

Change-Id: Ia7f099de291642ca672c5bf07555d688e09b3997