Fit RTC Detection, Issue #566

Corrected DSRTC and BQRTC drivers to properly restore the value of the NVRAM byte used for presence detection.

Thanks and credit to @MartinGieseCelonis for finding this.

Source/HBIOS/dsrtc.asm

@@ -482,6 +482,7 @@ DSRTC_DETECT:
 DSRTC_DETECT1:
 	PUSH	AF			; SAVE STATUS
 	LD	A,(DSRTC_TEMP)		; GET SAVED VALUE
+	LD	E,A			; TO E
 	LD	C,30			; NVRAM INDEX 30
 	CALL	DSRTC_SETBYT		; SAVE IT
 	POP	AF			; RECOVER STATUS

Source/HBIOS/rp5rtc.asm

@@ -136,7 +136,7 @@ RP5RTC_DETECT:
 
 RP5RTC_DETECT1:
 	PUSH	AF			; SAVE STATUS
-	LD	A, L			; GET SAVED VALUE
+	LD	E, L			; GET SAVED VALUE
 	LD	C, 0 			; NVRAM INDEX 0
 	CALL	RP5RTC_SETBYT		; SAVE IT
 	POP	AF			; RECOVER STATUS