mailbox: Remove depends on HAS_DMA in case of platform dependency

Remove dependencies on HAS_DMA where a Kconfig symbol depends on another
symbol that implies HAS_DMA, and, optionally, on "|| COMPILE_TEST".
In most cases this other symbol is an architecture or platform specific
symbol, or PCI.

Generic symbols and drivers without platform dependencies keep their
dependencies on HAS_DMA, to prevent compiling subsystems or drivers that
cannot work anyway.

This simplifies the dependencies, and allows to improve compile-testing.

Signed-off-by: Geert Uytterhoeven <[e-mail]>
Reviewed-by: Mark Brown <[e-mail]>
Acked-by: Robin Murphy <[e-mail]>
Signed-off-by: Jassi Brar <[e-mail]>

drivers/mailbox/Kconfig

···
 config BCM_PDC_MBOX
 	tristate "Broadcom FlexSparx DMA Mailbox"
 	depends on ARCH_BCM_IPROC || COMPILE_TEST
-	depends on HAS_DMA
 	help
 	  Mailbox implementation for the Broadcom FlexSparx DMA ring manager,
 	  which provides access to various offload engines on Broadcom
···
 	tristate "Broadcom FlexRM Mailbox"
 	depends on ARM64
 	depends on ARCH_BCM_IPROC || COMPILE_TEST
-	depends on HAS_DMA
 	select GENERIC_MSI_IRQ_DOMAIN
 	default m if ARCH_BCM_IPROC
 	help