usb: ehci: Get rid of CONFIG_SYS_USB_EHCI_MAX_ROOT_PORTS

EHC reports supported maximum number of ports in the HCSPARAMS
register, so it's unnecessary to use a hardcoded config option
CONFIG_SYS_USB_EHCI_MAX_ROOT_PORTS.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Stefan Roese <sr@denx.de>
Tested-by: Stefan Roese <sr@denx.de>
diff --git a/drivers/usb/host/ehci.h b/drivers/usb/host/ehci.h
index 2ab830d..7c39bec 100644
--- a/drivers/usb/host/ehci.h
+++ b/drivers/usb/host/ehci.h
@@ -11,9 +11,8 @@
 
 #include <usb.h>
 
-#if !defined(CONFIG_SYS_USB_EHCI_MAX_ROOT_PORTS)
-#define CONFIG_SYS_USB_EHCI_MAX_ROOT_PORTS	2
-#endif
+/* Section 2.2.3 - N_PORTS */
+#define MAX_HC_PORTS		15
 
 /*
  * Register Space.
@@ -62,7 +61,7 @@
 	uint32_t _reserved_1_[6];
 	uint32_t or_configflag;
 #define FLAG_CF		(1 << 0)	/* true:  we'll support "high speed" */
-	uint32_t or_portsc[CONFIG_SYS_USB_EHCI_MAX_ROOT_PORTS];
+	uint32_t or_portsc[MAX_HC_PORTS];
 #define PORTSC_PSPD(x)		(((x) >> 26) & 0x3)
 #define PORTSC_PSPD_FS			0x0
 #define PORTSC_PSPD_LS			0x1