Update libstagefright_omx_soft name in vndk.go

The library was renamed.  Update the library name in vndk.go
accordingly.

Bug: 119423884
Test: Build walleye-svelte with no-vendor-variant VNDK enabled.
Change-Id: I6f42e021c62b6fe407d02e9e38463c4efa5dcea3
diff --git a/cc/config/vndk.go b/cc/config/vndk.go
index 99264f5..a08b0e6 100644
--- a/cc/config/vndk.go
+++ b/cc/config/vndk.go
@@ -135,7 +135,6 @@
 	"libstagefright_flacdec",
 	"libstagefright_foundation",
 	"libstagefright_omx",
-	"libstagefright_omx_soft",
 	"libstagefright_omx_utils",
 	"libstagefright_soft_aacdec",
 	"libstagefright_soft_aacenc",
@@ -158,6 +157,7 @@
 	"libstagefright_soft_vorbisdec",
 	"libstagefright_soft_vpxdec",
 	"libstagefright_soft_vpxenc",
+	"libstagefright_softomx",
 	"libstagefright_xmlparser",
 	"libsysutils",
 	"libtinyxml2",