x86/boot: Fix cmdline_find_option() prototype visibility

ac09c5f43c ("x86/boot: Build the command line parsing code unconditionally")

enabled building the command line parsing code unconditionally but it
forgot to remove the respective ifdeffery around the prototypes in the
misc.h header, leading to

  arch/x86/boot/compressed/acpi.c: In function ‘get_acpi_rsdp’:
  arch/x86/boot/compressed/acpi.c:37:8: warning: implicit declaration of function \
	  ‘cmdline_find_option’ [-Wimplicit-function-declaration]
    ret = cmdline_find_option("acpi_rsdp", val, MAX_ADDR_LEN);
          ^~~~~~~~~~~~~~~~~~~

for configs where neither CONFIG_EARLY_PRINTK nor CONFIG_RANDOMIZE_BASE
was defined.

Drop the ifdeffery in the header too.

Fixes: ac09c5f43c ("x86/boot: Build the command line parsing code unconditionally")
Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Chao Fan <fanc.fnst@cn.fujitsu.com>
Cc: x86@kernel.org
Link: https://lkml.kernel.org/r/5c51daf0.83pQEkvDZILqoSYW%lkp@intel.com
Link: https://lkml.kernel.org/r/20190205131352.GA27396@zn.tnic

arch/x86/boot/compressed/misc.h

@@ -66,11 +66,9 @@ static inline void debug_puthex(const char *s)
 
 #endif
 
-#if CONFIG_EARLY_PRINTK || CONFIG_RANDOMIZE_BASE
 /* cmdline.c */
 int cmdline_find_option(const char *option, char *buffer, int bufsize);
 int cmdline_find_option_bool(const char *option);
-#endif
 
 struct mem_vector {
 	unsigned long long start;