sparc: remove unneeded uapi/asm/statfs.h

statfs.h is listed in include/uapi/asm-generic/Kbuild, so Kbuild will
automatically generate it.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: David S. Miller <davem@davemloft.net>