Makefile: move doc & test targets to prepare

Since we moved the build setup to hang from `prepare`, move
the other targets as well. Otherwise, if one uses them without
having built the kernel, they will not have the setup ready.

Fixes: 295b4f2 ("Makefile: run Rust `build` on `prepare`")
Signed-off-by: Miguel Ojeda <[email protected]>

Author: ojeda

Makefile

@@ -1782,12 +1782,12 @@ rustavailable:
 #
 # Using the singular to avoid running afoul of `no-dot-config-targets`.
 PHONY += rustdoc
-rustdoc: prepare0
+rustdoc: prepare
 	$(Q)$(MAKE) $(build)=rust $@
 
 # Testing target
 PHONY += rusttest
-rusttest: prepare0
+rusttest: prepare
 	$(Q)$(MAKE) $(build)=rust $@
 
 # Formatting targets
@@ -1812,7 +1812,7 @@ rustfmtcheck: rustfmt
 
 # IDE support targets
 PHONY += rust-analyzer
-rust-analyzer: prepare0
+rust-analyzer: prepare
 	$(Q)$(MAKE) $(build)=rust $@
 
 # Misc