iopsys-econet: Remove global UNIFIED_PLATFORM flag

TCSUPPORT_FH_UNIFIED_PLATFORM flag was used as temporar fix for flash
mounting. As suggested by Eocnet this flag should not be set global.
Moved to kernel mtd driver instead.

Signed-off-by: Bartlomiej Grzeskowiak <bartlomiej.grzeskowiak@iopsys.eu>

iopsys-econet/en7562/UNION_EN7562_7915D_ActiveEthWan_KERNEL_5_4_demo.mak

@@ -429,7 +429,7 @@ TCSUPPORT_MULTICAST_SPEED=y
 # TCSUPPORT_IGMP_SNOOPING_V3 is not set
 TCSUPPORT_SMUX=y
 # TCSUPPORT_MULIF_WAN_SAME_MAC is not set
-TCSUPPORT_FH_UNIFIED_PLATFORM=y
+# TCSUPPORT_FH_UNIFIED_PLATFORM is not set
 TCSUPPORT_MTD_PARTITIONS_CMDLINE=y
 TCSUPPORT_PARTITIONS_CMDLINE_STR="1m[bootloader]a,64m[ioplinux]a,-[free]a"
 TCSUPPORT_MTD_PARTITION_NUM=9