MIPS: Include asm/delay.h for __{,n,u}delay()

MIPS: Include asm/delay.h for __{,n,u}delay()

arch/mips/lib/delay.c provides our implementations of the __delay(),
__ndelay() & __udelay() functions, but doesn't include the asm/delay.h
header which declares them. This leads to warnings from sparse:

  arch/mips/lib/delay.c:26:6: warning: symbol '__delay' was not
    declared. Should it be static?
  arch/mips/lib/delay.c:50:6: warning: symbol '__udelay' was not
    declared. Should it be static?
  arch/mips/lib/delay.c:58:6: warning: symbol '__ndelay' was not
    declared. Should it be static?

To keep checkpatch happy was well, include <linux/delay.h> rather than
<asm/delay.h> directly to get the declarations of __delay(), __ndelay() &
__udelay().

[ralf@linux-mips.org: Fixed to include <linux/delay.h.]

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: trivial@kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/17170/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>