RT93137 Fix the build issue because of the added function in envm.h.

This function only makes sense if CONFIG_ENVM is on (not the case for
the STM-SOM configuration).

cpu/arm_cortexm3/envm.h

@@ -31,6 +31,8 @@ void envm_init(void);
 # error "LPC43XX ENVM requires RAMCODE"
 #endif
 
+#if defined(CONFIG_ENVM)
+
 /*
  * Check if an address is in the eNVM.
  */
@@ -40,6 +42,8 @@ static inline int envm_addr(unsigned long addr)
 		addr < CONFIG_SYS_ENVM_BASE + CONFIG_SYS_ENVM_LEN;
 }
 
+#endif
+
 /*
  * Write a data buffer to eNVM.
  * Note that we need for this function to reside in RAM since it