urandom-seed: avoid PKG_NAME in define lines

> Avoid reuse of PKG_NAME in call, define and eval lines for consistency and
> readability. Write the full name instead.

Ref: https://openwrt.org/docs/guide-developer/packages

Signed-off-by: Sungbo Eo <mans0n@gorani.run>

package/system/urandom-seed/Makefile

@@ -9,7 +9,7 @@ PKG_BUILD_DIR := $(BUILD_DIR)/$(PKG_NAME)
 
 include $(INCLUDE_DIR)/package.mk
 
-define Package/$(PKG_NAME)
+define Package/urandom-seed
   SECTION:=base
   CATEGORY:=Base system
   DEPENDS:=+getrandom
@@ -25,7 +25,7 @@ define Build/Compile/Default
 endef
 Build/Compile = $(Build/Compile/Default)
 
-define Package/$(PKG_NAME)/install
+define Package/urandom-seed/install
 	$(CP) ./files/* $(1)/
 endef