rainier_defconfig: Add multi-target support

Through OpenBMC and PLDM file.io, Power10 will support multiple MRW
definitions as part of one driver.

In order to achieve this in a staged approach, this commit introduces a
new 'openpower-pnor-p10' package that still creates the expected
pnor-related artifacts and intermediate files, while also creating the
individual files for each of the PNOR partitions (PAYLOAD, BOOTKERNEL)
inside the images/mmc directory. Each of those files will be suffixed
with ".P10" for target-agnostic files, or "uppercase-xml-name" (i.e.,
RAINIER_2U_XML) for target-specific files.

This patch also creates packages rainier-2u-xml and rainier-4u-xml(based
on machine-xml) that are both built and included in rainier_defconfig,
with rainier_2u_xml also serving as the 'legacy' pnor for smooth
transitions purposes.

Several other packages makefiles had to be reworked, but that should
allow both legacy openpower-pnor as well as the new mmc variant to build.

Signed-off-by: Klaus Heinrich Kiwi <klaus@linux.vnet.ibm.com>
diff --git a/openpower/package/hcode-p10/hcode-p10.mk b/openpower/package/hcode-p10/hcode-p10.mk
index b7a9101..016202a 100644
--- a/openpower/package/hcode-p10/hcode-p10.mk
+++ b/openpower/package/hcode-p10/hcode-p10.mk
@@ -28,13 +28,19 @@
 ###################################
 # P10 Compilation
 
+ifeq ($(BR2_PACKAGE_OPENPOWER_PNOR_P10),y)
+BINARY_IONV_FILENAME=$(BR2_HOSTBOOT_P10_BINARY_IONV_FILENAME)
+else
+BINARY_IONV_FILENAME=$(BR2_HOSTBOOT_BINARY_IONV_FILENAME)
+endif
+
 HCODE_P10_ENV_VARS= CONFIG_FILE=$(BR2_EXTERNAL_OP_BUILD_PATH)/configs/hcode/$(BR2_HCODE_CONFIG_FILE) \
 	LD_LIBRARY_PATH=$(HOST_DIR)/usr/lib \
 	CROSS_COMPILER_PATH=$(PPE42_GCC_BIN) PPE_TOOL_PATH=$(CROSS_COMPILER_PATH) \
 	PPE_PREFIX=$(CROSS_COMPILER_PATH)/bin/powerpc-eabi- \
         SELF_REST_PREFIX=$(CROSS_COMPILER_PATH)/bin/powerpc-eabi- \
 	RINGFILEPATH=$(STAGING_DIR)/hostboot_binaries __EKB_PREFIX=$(CXXPATH) \
-	CONFIG_IONV_FILE_LOCATION=$(STAGING_DIR)/hostboot_binaries/$(BR2_HOSTBOOT_BINARY_IONV_FILENAME) \
+	CONFIG_IONV_FILE_LOCATION=$(STAGING_DIR)/hostboot_binaries/$(BINARY_IONV_FILENAME) \
 	CONFIG_INCLUDE_IONV=$(BR2_HCODE_INCLUDE_IONV) OPENPOWER_BUILD=1
 
 define HCODE_P10_INSTALL_IMAGES_CMDS