csky: fixup compile error with pte_alloc

Commit: 4cf58924 remove the address argument of pte_alloc without
modify csky related code. linux-5.0-rc1 compile failed with csky.

Remove the unnecessary address testing in pte_alloc().

Signed-off-by: Guo Ren <ren_guo@c-sky.com>
Cc: Joel Fernandes (Google) <joel@joelfernandes.org>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>