build: nuvoton-lpc: Add `NUVOTON_LPC` project_arguments

The `NUVOTON_LPC` is not defined when building for `nuvoton-lpc`
which resulted in the blob loading to fail on the BMC.

Change-Id: I5833855ee696860ce41b3f136c20060c7638f8df
Signed-off-by: Willy Tu <wltu@google.com>
diff --git a/meson.build b/meson.build
index 0246aa2..75b5ead 100644
--- a/meson.build
+++ b/meson.build
@@ -94,7 +94,7 @@
 
 lpc_type_combo_map = {
   'aspeed-lpc'       : '-DASPEED_LPC',
-  'nuvoton-lpc'      : '-DASPEED_LPC',
+  'nuvoton-lpc'      : '-DNUVOTON_LPC',
 }
 
 foreach option_key, option_value : lpc_type_combo_map