HT32: TIMv1: gpt_lld_init: Fix reference to GPTD_BFTM1

Fixes issue where GPTD_BFTM0 would point to BFTM1 when
HT32_GPT_USE_BFTM0 and HT32_GPT_USE_BFTM1 are defined True (and leaving
GPTD_BFTM1 unused).

Additionally, this fixes undeclared variable warning when only
HT32_GPT_USE_BFTM1 is defined True.

os/hal/ports/HT32/LLD/TIMv1/hal_gpt_lld.c

@@ -101,7 +101,7 @@ void gpt_lld_init(void) {
 #endif
 #if HT32_GPT_USE_BFTM1 == TRUE
     gptObjectInit(&GPTD_BFTM1);
-    GPTD_BFTM0.BFTM = BFTM1;
+    GPTD_BFTM1.BFTM = BFTM1;
 #endif
 }