Permit /system/lib/vndk-sp/hw/ for 'sphal' namespace

android.hidl.memory@1.0-impl.so is a SP-HAL located in
/system/lib/vndk-sp/hw. This can't be moved to /vendor/lib since it is a
framework HAL.

Bug: 62930720
Test: 2017 pixel builds and boots with BOARD_VNDK_VERSION on
Merged-In: I9c456983ef68120c5e8c629efc6dd66a26220ecb
Change-Id: I9c456983ef68120c5e8c629efc6dd66a26220ecb
(cherry picked from commit 7d4cf3fd)