treewide: remove BUILD_PARALLEL from CMake packages

It's already default. The only exception is mt76 which has Ninja
disabled.

Found with:

git grep BUILD_PARALLEL | cut -d ':' -f 1 | sort -u > par
git grep cmake.mk | cut -d ':' -f 1 > cmake
comm -1 -2 par cmake

Signed-off-by: Rosen Penev <rosenp@gmail.com>

package/network/utils/umbim/Makefile

@@ -13,8 +13,6 @@ PKG_MAINTAINER:=John Crispin <john@phrozen.org>
 PKG_LICENSE:=GPL-2.0
 PKG_LICENSE_FILES:=
 
-PKG_BUILD_PARALLEL:=1
-
 PKG_FLAGS:=nonshared
 
 include $(INCLUDE_DIR)/package.mk

package/network/utils/uqmi/Makefile

@@ -13,8 +13,6 @@ PKG_MAINTAINER:=Matti Laakso <malaakso@elisanet.fi>
 PKG_LICENSE:=GPL-2.0
 PKG_LICENSE_FILES:=
 
-PKG_BUILD_PARALLEL:=1
-
 PKG_FLAGS:=nonshared
 
 include $(INCLUDE_DIR)/package.mk