Remove Fuchsia support from Soong

Bug: 194215932
Test: m checkbuild
Change-Id: Id7d3964d9417f8b0938af9b168bb4c00cebe9390

android/module.go

@@ -325,7 +325,6 @@ type BaseModuleContext interface {
 	Host() bool
 	Device() bool
 	Darwin() bool
-	Fuchsia() bool
 	Windows() bool
 	Debug() bool
 	PrimaryArch() bool
@@ -2563,10 +2562,6 @@ func (b *baseModuleContext) Darwin() bool {
 	return b.os == Darwin
 }
 
-func (b *baseModuleContext) Fuchsia() bool {
-	return b.os == Fuchsia
-}
-
 func (b *baseModuleContext) Windows() bool {
 	return b.os == Windows
 }