upower: add pm-utils to RRECOMMENDS

This fixes:

dbus-daemon[207]: (upowerd:401): UPower-Linux-WARNING **: failed to run script: Failed to execute child process "/usr/bin/pm-is-supported" (No such file or directory)
dbus-daemon[207]: (upowerd:401): UPower-Linux-WARNING **: failed to run script: Failed to execute child process "/usr/bin/pm-is-supported" (No such file or directory)
dbus-daemon[207]: (upowerd:401): UPower-WARNING **: failed to run script: Failed to execute child process "/usr/sbin/pm-powersave" (No such file or directory)

Signed-off-by: Koen Kooi <koen@dominion.thruhere.net>