Correct the arch name for armv7a on NuttX (#1678)

product-mini/platforms/nuttx/wamr.mk

@@ -8,7 +8,7 @@ SHARED_ROOT := wamr/core/shared
 ifeq ($(CONFIG_ARCH_ARMV6M),y)
 WAMR_BUILD_TARGET := THUMBV6M
 else ifeq ($(CONFIG_ARCH_ARMV7A),y)
-WAMR_BUILD_TARGET := THUMBV7A
+WAMR_BUILD_TARGET := THUMBV7
 else ifeq ($(CONFIG_ARCH_ARMV7M),y)
 WAMR_BUILD_TARGET := THUMBV7EM
 else ifeq ($(CONFIG_ARCH_ARMV8M),y)