MIPS: Make CONFIG_SYS_DCACHE_LINE_SIZE int, not hex

For consistency with the other cache-related Kconfig entries & the
values actually set by boards, make CONFIG_SYS_DCACHE_LINE_SIZE an int
entry instead of a hex entry.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Fixes: 372286217f ("MIPS: Split I & D cache line size config")

arch/mips/Kconfig

@@ -253,7 +253,7 @@ config SYS_DCACHE_SIZE
 	  The total size of the L1 Dcache, if known at compile time.
 
 config SYS_DCACHE_LINE_SIZE
-	hex
+	int
 	default 0
 	help
 	  The size of L1 Dcache lines, if known at compile time.