powerpc: remove redundant 'default n' from Kconfig-s

'default n' is the default value for any bool or tristate Kconfig
setting so there is no need to write it explicitly.

Also since commit f467c5640c ("kconfig: only write '# CONFIG_FOO
is not set' for visible symbols") the Kconfig behavior is the same
regardless of 'default n' being present or not:

    ...
    One side effect of (and the main motivation for) this change is making
    the following two definitions behave exactly the same:

        config FOO
                bool

        config FOO
                bool
                default n

    With this change, neither of these will generate a
    '# CONFIG_FOO is not set' line (assuming FOO isn't selected/implied).
    That might make it clearer to people that a bare 'default n' is
    redundant.
    ...

Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/platforms/ps3/Kconfig

@@ -49,7 +49,6 @@ config PS3_HTAB_SIZE
 config PS3_DYNAMIC_DMA
 	depends on PPC_PS3
 	bool "PS3 Platform dynamic DMA page table management"
-	default n
 	help
 	  This option will enable kernel support to take advantage of the
 	  per device dynamic DMA page table management provided by the Cell
@@ -89,7 +88,6 @@ config PS3_SYS_MANAGER
 config PS3_REPOSITORY_WRITE
 	bool "PS3 Repository write support" if PS3_ADVANCED
 	depends on PPC_PS3
-	default n
 	help
 	  Enables support for writing to the PS3 System Repository.