am335x_evm: Add am335x_evm_usbspl build target

We add USB (RNDIS gadget) SPL support as a separate target.  We need to
pull out YMODEM support in order to be a small enough target binary.

Signed-off-by: Tom Rini <trini@ti.com>

board/ti/am335x/board.c

@@ -73,7 +73,7 @@ static inline int board_is_idk(void)
 	return !strncmp(header.config, "SKU#02", 6);
 }
 
-static int board_is_gp_evm(void)
+static int __maybe_unused board_is_gp_evm(void)
 {
 	return !strncmp("A33515BB", header.name, 8);
 }

boards.cfg

@@ -239,6 +239,7 @@ am335x_evm_uart2             arm         armv7       am335x              ti
 am335x_evm_uart3             arm         armv7       am335x              ti             am33xx      am335x_evm:SERIAL4,CONS_INDEX=4
 am335x_evm_uart4             arm         armv7       am335x              ti             am33xx      am335x_evm:SERIAL5,CONS_INDEX=5
 am335x_evm_uart5             arm         armv7       am335x              ti             am33xx      am335x_evm:SERIAL6,CONS_INDEX=6
+am335x_evm_usbspl            arm         armv7       am335x              ti             am33xx      am335x_evm:SERIAL1,CONS_INDEX=1,SPL_USBETH_SUPPORT
 pcm051                       arm         armv7       pcm051              phytec         am33xx      pcm051
 highbank                     arm         armv7       highbank            -              highbank
 mx51_efikamx                 arm         armv7       mx51_efikamx        genesi         mx5		mx51_efikamx:MACH_TYPE=MACH_TYPE_MX51_EFIKAMX,IMX_CONFIG=board/genesi/mx51_efikamx/imximage_mx.cfg

include/configs/am335x_evm.h

@@ -365,11 +365,9 @@
 /* disable host part of MUSB in SPL */
 #undef CONFIG_MUSB_HOST
 /*
- * Disable UART, CPSW ethernet support and extra environment settings so we
- * will fit within 101KiB.
+ * Disable CPSW SPL support so we fit within the 101KiB limit.
  */
 #undef CONFIG_SPL_ETH_SUPPORT
-#undef CONFIG_SPL_YMODEM_SUPPORT
 #endif
 
 /*