net: smc911x: Drop redundant CONFIG_SMC911X_16_BIT Kconfig symbol

The SMC911x Ethernet driver needs to know which accessor functions it
can use to access the MMIO registers. For that reason we have a Kconfig
choice between 16 and 32-bit bus width.

Since it's only those two options that we (and the Linux kernel)
support, and there does not seem to be any evidence of another bus
width anywhere, limit the Kconfig construct to a simple symbol.

This simplifies the code and allows a later rework to be much easier.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Reviewed-by: Ramon Fried <rfried.dev@gmail.com>
diff --git a/drivers/net/Kconfig b/drivers/net/Kconfig
index 9fc28b1..2a7c8f9 100644
--- a/drivers/net/Kconfig
+++ b/drivers/net/Kconfig
@@ -548,21 +548,14 @@
 	  of the device (I/O space)
 endif #DM_ETH
 
-choice
-	prompt "SMC911X bus width"
-	default SMC911X_16_BIT
-
 config SMC911X_32_BIT
-	bool "Enable 32-bit interface"
-
-config SMC911X_16_BIT
-	bool "Enable 16-bit interface"
+	bool "Enable SMC911X 32-bit interface"
+	default n
 	help
-	  Define this if data bus is 16 bits. If your processor
-	  automatically converts one 32 bit word to two 16 bit
-	  words you may also try CONFIG_SMC911X_32_BIT.
+	  Define this if data bus is 32 bits. If your processor use a
+	  narrower 16 bit bus or cannot convert one 32 bit word to two 16 bit
+	  words, leave this to "n".
 
-endchoice
 endif #SMC911X
 
 config SUN7I_GMAC
diff --git a/drivers/net/smc911x.c b/drivers/net/smc911x.c
index 7b79831..d596d96 100644
--- a/drivers/net/smc911x.c
+++ b/drivers/net/smc911x.c
@@ -48,12 +48,6 @@
 
 #define DRIVERNAME "smc911x"
 
-#if defined (CONFIG_SMC911X_32_BIT) && \
-	defined (CONFIG_SMC911X_16_BIT)
-#error "SMC911X: Only one of CONFIG_SMC911X_32_BIT and \
-	CONFIG_SMC911X_16_BIT shall be set"
-#endif
-
 #if defined (CONFIG_SMC911X_32_BIT)
 static u32 smc911x_reg_read(struct smc911x_priv *priv, u32 offset)
 {
@@ -64,7 +58,7 @@
 {
 	writel(val, priv->iobase + offset);
 }
-#elif defined (CONFIG_SMC911X_16_BIT)
+#else
 static u32 smc911x_reg_read(struct smc911x_priv *priv, u32 offset)
 {
 	return (readw(priv->iobase + offset) & 0xffff) |
@@ -75,9 +69,7 @@
 	writew(val & 0xffff, priv->iobase + offset);
 	writew(val >> 16, priv->iobase + offset + 2);
 }
-#else
-#error "SMC911X: undefined bus width"
-#endif /* CONFIG_SMC911X_16_BIT */
+#endif /* CONFIG_SMC911X_32_BIT */
 
 static u32 smc911x_get_mac_csr(struct smc911x_priv *priv, u8 reg)
 {