phosphor-software-manager: Add ACTIVE_BMC_MAX_ALLOWED config

For static flash layout, configure ACTIVE_BMC_MAX_ALLOWED to 1, because
it has only one active BMC image;
For ubi-fs, configure ACTIVE_BMC_MAX_ALLOWED to 2, because ubi-fs
assumes there are two BMC images by default.

Resolves openbmc/phosphor-bmc-code-mgmt#2

Tested: Verify that ACTIVE_BMC_MAX_ALLOWED is set to 1 for Romulus
        build, and set to 2 for Witherspoon build.

(From meta-phosphor rev: bf3edf1ce09f19836c38c2dd43ab4e50664fc46e)

Change-Id: I60e49c14bda25547fde9a2308470ed164ebbd249
Signed-off-by: Lei YU <mine260309@gmail.com>
Signed-off-by: Brad Bishop <bradleyb@fuzziesquirrel.com>
diff --git a/meta-phosphor/classes/phosphor-software-manager-ubi-fs.bbclass b/meta-phosphor/classes/phosphor-software-manager-ubi-fs.bbclass
index 42e08ce..4d146c1 100644
--- a/meta-phosphor/classes/phosphor-software-manager-ubi-fs.bbclass
+++ b/meta-phosphor/classes/phosphor-software-manager-ubi-fs.bbclass
@@ -12,11 +12,13 @@
 
 # Remove default configs
 EXTRA_OECONF_remove_df-obmc-ubi-fs += " \
+    ACTIVE_BMC_MAX_ALLOWED=1 \
     MEDIA_DIR=/run/media \
 "
 
 # Add ubi-fs configs
 EXTRA_OECONF_append_df-obmc-ubi-fs += " \
+    ACTIVE_BMC_MAX_ALLOWED=2 \
     MEDIA_DIR=/media \
 "
 
diff --git a/meta-phosphor/common/recipes-phosphor/flash/phosphor-software-manager.bb b/meta-phosphor/common/recipes-phosphor/flash/phosphor-software-manager.bb
index eb2468d..0b6723c 100644
--- a/meta-phosphor/common/recipes-phosphor/flash/phosphor-software-manager.bb
+++ b/meta-phosphor/common/recipes-phosphor/flash/phosphor-software-manager.bb
@@ -57,6 +57,7 @@
     virtual-obmc-image-manager \
 "
 EXTRA_OECONF += " \
+    ACTIVE_BMC_MAX_ALLOWED=1 \
     MEDIA_DIR=/run/media \
 "