Update syscalls_stubs.cpp (project-chip#27187)

Fix the redundant assignment equals sign, which causes compilation to fail.

Author: ihidchaos

examples/platform/silabs/syscalls_stubs.cpp

@@ -174,7 +174,7 @@ int __attribute__((weak)) _read(int file, char * ptr, int len)
 {
     (void) file;
 #if SILABS_LOG_OUT_UART
-    return = uartConsoleRead(ptr, len);
+    return uartConsoleRead(ptr, len);
 #else
     (void) ptr;
     (void) len;