powerpc/cell: Drop CONFIG_TUNE_CELL in favour of CONFIG_CELL_CPU

The TUNE_CELL option allows you to build a kernel that runs on multiple
CPUs but is tuned (ie. optimised) to run on Cell CPUs. Now days no one
is building a distro in that fashion, and any users who are building
custom kernels for their Cell machines are better off building with
CONFIG_CELL_CPU, which builds a kernel that only runs on Cell and
therefore can be optimised even more aggresively.

Dropping the option also avoids confusing other users, who are presented
with an option to tune for Cell when they are not building for a Cell
CPU at all.

Suggested-by: Thomas Huth <[e-mail]>
Signed-off-by: Michael Ellerman <[e-mail]>

arch/powerpc/Makefile

···
 endif
 endif
 
-CFLAGS-$(CONFIG_TUNE_CELL) += $(call cc-option,-mtune=cell)
-
 asinstr := $(call as-instr,lis 9$(comma)foo@high,-DHAVE_AS_ATHIGH=1)
 
 KBUILD_CPPFLAGS	+= -Iarch/$(ARCH) $(asinstr)

arch/powerpc/configs/cell_defconfig

···
 CONFIG_PPC64=y
-CONFIG_TUNE_CELL=y
+CONFIG_CELL_CPU=y
 CONFIG_ALTIVEC=y
 CONFIG_SMP=y
 CONFIG_NR_CPUS=4

arch/powerpc/configs/ps3_defconfig

···
 CONFIG_PPC64=y
-CONFIG_TUNE_CELL=y
+CONFIG_CELL_CPU=y
 CONFIG_ALTIVEC=y
 CONFIG_SMP=y
 CONFIG_NR_CPUS=2

arch/powerpc/platforms/Kconfig.cputype

···
 	depends on PPC32 && PPC_BOOK3S
 	select PPC_HAVE_PMU_SUPPORT
 
-config TUNE_CELL
-	bool "Optimize for Cell Broadband Engine"
-	depends on PPC64 && PPC_BOOK3S
-	help
-	  Cause the compiler to optimize for the PPE of the Cell Broadband
-	  Engine. This will make the code run considerably faster on Cell
-	  but somewhat slower on other machines. This option only changes
-	  the scheduling of instructions, not the selection of instructions
-	  itself, so the resulting kernel will keep running on all other
-	  machines.
-
 # this is temp to handle compat with arch=ppc
 config 8xx
 	bool