Rainier power supply presence detects

Update rainier.conf to indicate the four power supply instances.

Update bbappend for Rainier SYSTEMD_LINK and SYSTEMD_ENVIRONMENT_FILE.

Add in subdirectory and power supply configuration files for GPIO
presence detect of the Rainier power supplies.

Use aspeed-gpio.sh from https://github.com/bradbishop/gpio-keys to
determine gpio-key values. Use 7-bit I2C addresses on BMC.

+-----+--------+----------+----+
| PSU | GPIO   | gpio-key | AA |
+-----+--------+----------+----+
| ps0 | GPIOS0 |    144   | 68 |
+-----+--------+----------+----+
| ps1 | GPIOS1 |    145   | 69 |
+-----+--------+----------+----+
| ps2 | GPIOS2 |    146   | 6a |
+-----+--------+----------+----+
| ps3 | GPIOS3 |    147   | 6b |
+-----+--------+----------+----+

(From meta-ibm rev: 3e8f174546cf440fda56ce47523030d4d403edbd)

Change-Id: Ia55f80e4d857e7a477385d73c12f9719e3065f95
Signed-off-by: Brandon Wyman <bjwyman@gmail.com>
Signed-off-by: Brad Bishop <bradleyb@fuzziesquirrel.com>
diff --git a/meta-ibm/meta-witherspoon/conf/machine/rainier.conf b/meta-ibm/meta-witherspoon/conf/machine/rainier.conf
index 628a45a..78ffbbc 100644
--- a/meta-ibm/meta-witherspoon/conf/machine/rainier.conf
+++ b/meta-ibm/meta-witherspoon/conf/machine/rainier.conf
@@ -1,6 +1,8 @@
 KERNEL_DEVICETREE = "aspeed-bmc-ibm-rainier.dtb"
 UBOOT_MACHINE = "evb-ast2600_defconfig"
 
+OBMC_POWER_SUPPLY_INSTANCES = "0 1 2 3"
+
 require conf/machine/include/ast2600.inc
 require conf/machine/include/obmc-bsp-common.inc
 require conf/machine/include/openpower.inc