[U-Boot] [RFC] Disable USB options for SPL build

[Sam Protsenko]

Hi All,

Since we are moving config options from include/configs/* to Kconfigs
and defconfigs, we can't do #ifdefs anymore. Example: in
include/configs/am43xx_evm.h you can see next code:

#if !defined(CONFIG_SPL_BUILD) || \
    (defined(CONFIG_SPL_BUILD) && defined(CONFIG_SPL_USBETH_SUPPORT))
#define CONFIG_USB_GADGET
...
#endif

So USB GADGET builds only for U-Boot, but doesn't builds for SPL.
But when defining the same CONFIG_USB_GADGET option in defconfig, we
can't do #ifdef code.

My question is, should we hardcode this in corresponding drivers
instead? Or perhaps it should be done in some more elegant way? Or we
can just forget about this and let it be built for both U-Boot and
SPL? Please share your thoughts on this matter.

Thanks!