mISDN: remove unused vpm_read_address and cpld_read_reg functions

clang with W=1 reports
drivers/isdn/hardware/mISDN/hfcmulti.c:667:1: error: unused function
  'vpm_read_address' [-Werror,-Wunused-function]
vpm_read_address(struct hfc_multi *c)
^

drivers/isdn/hardware/mISDN/hfcmulti.c:643:1: error: unused function
  'cpld_read_reg' [-Werror,-Wunused-function]
cpld_read_reg(struct hfc_multi *hc, unsigned char reg)
^

These functions are not used, so remove them.
Reported-by: Simon Horman <simon.horman@corigine.com>
Signed-off-by: Tom Rix <trix@redhat.com>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Link: https://lore.kernel.org/r/20230323161343.2633836-1-trix@redhat.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/isdn/hardware/mISDN/hfcmulti.c

@@ -639,23 +639,6 @@ cpld_write_reg(struct hfc_multi *hc, unsigned char reg, unsigned char val)
 	return;
 }
 
-static inline unsigned char
-cpld_read_reg(struct hfc_multi *hc, unsigned char reg)
-{
-	unsigned char bytein;
-
-	cpld_set_reg(hc, reg);
-
-	/* Do data pin read low byte */
-	HFC_outb(hc, R_GPIO_OUT1, reg);
-
-	enablepcibridge(hc);
-	bytein = readpcibridge(hc, 1);
-	disablepcibridge(hc);
-
-	return bytein;
-}
-
 static inline void
 vpm_write_address(struct hfc_multi *hc, unsigned short addr)
 {
@@ -663,20 +646,6 @@ vpm_write_address(struct hfc_multi *hc, unsigned short addr)
 	cpld_write_reg(hc, 1, 0x01 & (addr >> 8));
 }
 
-static inline unsigned short
-vpm_read_address(struct hfc_multi *c)
-{
-	unsigned short addr;
-	unsigned short highbit;
-
-	addr = cpld_read_reg(c, 0);
-	highbit = cpld_read_reg(c, 1);
-
-	addr = addr | (highbit << 8);
-
-	return addr & 0x1ff;
-}
-
 static inline unsigned char
 vpm_in(struct hfc_multi *c, int which, unsigned short addr)
 {