Bump skiboot to v5.7-rc1

Andrew Donnellan (1):
      npu2: Use phys-map to get MMIO BARs

Benjamin Herrenschmidt (2):
      phb4: Fix number of index bits in IODA tables
      cpu: Cleanup AMR and IAMR when re-initializing CPUs

Michael Neuling (1):
      Set POWER9 RPR SPR

Stewart Smith (1):
      skiboot-5.7-rc1 release notes

Signed-off-by: Stewart Smith <stewart@linux.vnet.ibm.com>
diff --git a/openpower/package/skiboot/Config.in b/openpower/package/skiboot/Config.in
index 59c0ad6..ddff494 100644
--- a/openpower/package/skiboot/Config.in
+++ b/openpower/package/skiboot/Config.in
@@ -31,7 +31,7 @@
 
 config BR2_SKIBOOT_VERSION
 	string
-	default "skiboot-5.6.0-158-ga1e0a047b2a0" if BR2_SKIBOOT_LATEST_VERSION
+	default "v5.7-rc1" if BR2_SKIBOOT_LATEST_VERSION
 	default BR2_SKIBOOT_CUSTOM_VERSION_VALUE \
 		if BR2_SKIBOOT_CUSTOM_VERSION