PRU shared memory without root privileges request

**Describe the bug**
Servo module refuses to initialize when not root

**To Reproduce**
Call rc_servo_init() from a program running as an ordinary user

**Expected behavior**
Servo subsystem should initialize.

**Screenshots**
Console error message is:
ERROR: in rc_pru_shared_mem_ptr could not open /dev/mem: Permission denied
Need to be root to access PRU shared memory
ERROR in rc_servo_init, failed to map shared memory pointer

**Platform information**
Debian version is stretch, with apt-get update/upgrade/dist-upgrade run today

uname -a returns:
Linux beaglebone 4.9.45-ti-r57 #1 SMP PREEMPT Fri Aug 25 22:58:38 UTC 2017 armv7l GNU/Linux

rc_test_drivers returns:
Kernel: 4.9.45-ti-r57
BeagleBoard.org Debian Image 2017-08-31
Debian: 9.5

PASSED: gpio 0
PASSED: gpio 1
PASSED: gpio 2
PASSED: gpio 3
PASSED: pwm1
PASSED: pwm2
PASSED: eqep0
PASSED: eqep1
PASSED: eqep2
PASSED: pru-rproc
PASSED: uart1
PASSED: uart2
PASSED: uart4
PASSED: uart5
PASSED: i2c1
PASSED: i2c2
PASSED: spi
PASSED: LED
ERROR: ADC iio driver not loaded