package/linux-pam: add missing BR2_USE_MMU dependency on comment

BR2_PACKAGE_LINUX_PAM depends on BR2_USE_MMU, but this dependency is
not taken into account in the Config.in comment, which this commit
fixes.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

package/linux-pam/Config.in

@@ -11,5 +11,6 @@ config BR2_PACKAGE_LINUX_PAM
 	  http://linux-pam.org
 
 comment "linux-pam needs a toolchain w/ wchar, locale, dynamic library"
+	depends on BR2_USE_MMU
 	depends on !(BR2_ENABLE_LOCALE && BR2_USE_WCHAR) \
 		|| BR2_STATIC_LIBS