mips: fix r3k_cache_init build regression

My earlier patch removed __weak function declarations that used to be
turned into wild branches by the linker, instead causing a link failure
when the called functions are unavailable:

mips-linux-ld: arch/mips/mm/cache.o: in function `cpu_cache_init':
cache.c:(.text+0x670): undefined reference to `r3k_cache_init'

The __weak method seems suboptimal, so rather than putting that back, make
the function calls conditional on the Kconfig symbol that controls the
compilation.

[akpm@linux-foundation.org: fix whitespace while we're in there]
Link: https://lkml.kernel.org/r/20231214205506.310402-1-arnd@kernel.org
Fixes: 66445677 ("mips: move cache declarations into header")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reported-by: kernelci.org bot <bot@kernelci.org>
Cc: Jiaxun Yang <jiaxun.yang@flygoat.com>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

arch/mips/mm/cache.c

@@ -205,16 +205,13 @@ static inline void setup_protection_map(void)
 
 void cpu_cache_init(void)
 {
-	if (cpu_has_3k_cache) {
+	if (IS_ENABLED(CONFIG_CPU_R3000) && cpu_has_3k_cache)
 		r3k_cache_init();
-	}
-	if (cpu_has_4k_cache) {
+	if (IS_ENABLED(CONFIG_CPU_R4K_CACHE_TLB) && cpu_has_4k_cache)
 		r4k_cache_init();
-	}
 
-	if (cpu_has_octeon_cache) {
+	if (IS_ENABLED(CONFIG_CPU_CAVIUM_OCTEON) && cpu_has_octeon_cache)
 		octeon_cache_init();
-	}
 
 	setup_protection_map();
 }