skiboot: bump garrison to latest skiboot master

As Garrison is still under active development, bump it from an older
skiboot master revision to the current one.

Signed-off-by: Stewart Smith <stewart@linux.vnet.ibm.com>
diff --git a/openpower/configs/garrison_defconfig b/openpower/configs/garrison_defconfig
index f62e2fb..7cdd7fc 100644
--- a/openpower/configs/garrison_defconfig
+++ b/openpower/configs/garrison_defconfig
@@ -36,7 +36,7 @@
 BR2_PACKAGE_SKIBOOT=y
 BR2_PACKAGE_SKIBOOT_EMBED_PAYLOAD=n
 BR2_SKIBOOT_CUSTOM_VERSION=y
-BR2_SKIBOOT_CUSTOM_VERSION_VALUE="e6b2e38abb906023c1ef3631b21ad00d26fc0b5f"
+BR2_SKIBOOT_CUSTOM_VERSION_VALUE="5f25590fd430265e69190aaa50f019e8dadad293"
 
 # petitboot requirements
 BR2_ENABLE_LOCALE_PURGE=y