meta-ibm: Use proper path names in service files

Don't use /usr/bin/env, it's an antipattern.

Signed-off-by: Matt Spinler <spinler@us.ibm.com>
Change-Id: If388f5427bb2ca45718d0ca99452bf3f147861dd
diff --git a/meta-ibm/meta-romulus/recipes-phosphor/gpio/id-button/id-button-pressed.service b/meta-ibm/meta-romulus/recipes-phosphor/gpio/id-button/id-button-pressed.service
index f633fc3..c4f939c 100644
--- a/meta-ibm/meta-romulus/recipes-phosphor/gpio/id-button/id-button-pressed.service
+++ b/meta-ibm/meta-romulus/recipes-phosphor/gpio/id-button/id-button-pressed.service
@@ -6,5 +6,4 @@
 
 [Service]
 Type=oneshot
-ExecStart=/usr/bin/env toggle_identify_led.sh
-SyslogIdentifier=id-button
+ExecStart=/usr/bin/toggle_identify_led.sh