[OE-core] [meta-intel] n450-audio.bb: ${POKYBASE} --> ${COREBASE}

[Cui, Dexuan]

Currently n450 can't build due to the issue:

diff --git a/meta-n450/recipes-bsp/n450-audio/n450-audio.bb b/meta-n450/recipes-bsp/n450-audio/n450-audio.bb
index 90ec267..27904e3 100644
--- a/meta-n450/recipes-bsp/n450-audio/n450-audio.bb
+++ b/meta-n450/recipes-bsp/n450-audio/n450-audio.bb
@@ -2,7 +2,7 @@ SUMMARY = "Provide a basic init script to enable audio"
 DESCRIPTION = "Set the volume and unmute the Front mixer setting during boot."
 SECTION = "base"
 LICENSE = "MIT"
-LIC_FILES_CHKSUM = "file://${POKYBASE}/LICENSE;md5=3f40d7994397109285ec7b81fdeb3b58"
+LIC_FILES_CHKSUM = "file://${COREBASE}/LICENSE;md5=3f40d7994397109285ec7b81fdeb3b58"

 PR = "r4"

Thanks,
-- Dexuan