[WATCHDOG] fix watchdog/shwdt.c compilation

This patch fixes the following compile errors caused by
commit 70b814ec


([WATCHDOG 45/57] shwdt: coding style, cleanup, switch to unlocked_io):

<--  snip  -->

...
  CC      drivers/watchdog/shwdt.o
shwdt.c:64: error: 'WTCSR_CKS_4096' undeclared here (not in a function)
shwdt.c: In function 'sh_wdt_start':
shwdt.c:92: error: 'wdt_lock' undeclared (first use in this function)
shwdt.c:92: error: (Each undeclared identifier is reported only once
shwdt.c:92: error: for each function it appears in.)
shwdt.c:97: error: implicit declaration of function 'sh_wdt_read_csr'
shwdt.c:98: error: 'WTCSR_WT' undeclared (first use in this function)
shwdt.c:99: error: implicit declaration of function 'sh_wdt_write_csr'
shwdt.c:101: error: implicit declaration of function 'sh_wdt_write_cnt'
shwdt.c:112: error: 'WTCSR_TME' undeclared (first use in this function)
shwdt.c:113: error: 'WTCSR_RSTS' undeclared (first use in this function)
shwdt.c: In function 'sh_wdt_stop':
shwdt.c:142: error: 'wdt_lock' undeclared (first use in this function)
shwdt.c:147: error: 'WTCSR_TME' undeclared (first use in this function)
shwdt.c: In function 'sh_wdt_keepalive':
shwdt.c:160: error: 'wdt_lock' undeclared (first use in this function)
shwdt.c: In function 'sh_wdt_set_heartbeat':
shwdt.c:176: error: 'wdt_lock' undeclared (first use in this function)
shwdt.c: In function 'sh_wdt_ping':
shwdt.c:192: error: 'wdt_lock' undeclared (first use in this function)
shwdt.c:197: error: 'WTCSR_IOVF' undeclared (first use in this function)
shwdt.c: At top level:
shwdt.c:417: error: conflicting type qualifiers for 'sh_wdt_info'
shwdt.c:71: error: previous declaration of 'sh_wdt_info' was here
make[3]: *** [drivers/watchdog/shwdt.o] Error 1

<--  snip  -->

Reported-by: Adrian Bunk <bunk@kernel.org>
Signed-off-by: Adrian Bunk <bunk@kernel.org>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>