Revert "sh: add missing EXPORT_SYMBOL() for __delay"

This reverts commit d1f56f31.

__delay() is an internal implementation detail on several architectures.
Drivers should not call __delay() directly, as it has non-standardized
semantics, or may not even exist.
Hence there is no need to export __delay() to modules.

See also include/asm-generic/delay.h:

    /* Undefined functions to get compile-time errors */
    ...
    extern void __delay(unsigned long loops);

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Rich Felker <dalias@libc.org>