meta-openpower: fix shellcheck issues

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: I35a9ffed937919467dec62a1fbff729f4a51366c
diff --git a/meta-openpower/recipes-bsp/pdata/files/power-target.sh b/meta-openpower/recipes-bsp/pdata/files/power-target.sh
index 4a02419..1a871d4 100755
--- a/meta-openpower/recipes-bsp/pdata/files/power-target.sh
+++ b/meta-openpower/recipes-bsp/pdata/files/power-target.sh
@@ -1,3 +1,5 @@
+#!/bin/sh
+
 # Command line debug tools like pdbg and ecmd requires
 # PDBG_DTB environment variable.
 # attributes tool required PDBG_DTB, PDATA_INFODB and PDATA_ATTR_OVERRIDE