The TOPIC97 and TOPIC100 seem to have a special register in the exca

space that enables low voltage operation (and maybe other stuff).
Enable the bits in this register so low voltage 16-bit cards may work.

Existance noticed in NetBSD driver.

sys/dev/exca/excareg.h

@@ -402,6 +402,12 @@
 #define EXCA_O2CC_IREQ_INTC			0x80
 #define EXCA_O2CC_STSCHG_INTC			0x20
 
+/*
+ * TOPIC specific registers
+ */
+#define EXCA_TOPIC97_CTRL			0x3e
+#define EXCA_TOPIC97_CTRL_LV_MASK		0x03
+
 /* Plug and play */
 #define EXCA_PNP_ACTIONTEC	0x1802A904	/* AEI0218 */
 #define EXCA_PNP_IBM3765	0x65374d24	/* IBM3765 */