CONFIG_ARCH_BCM2835 is not available for thedefaultarchitecture x86.
Result is shown for architecture arm

Broadcom BCM2835 family

modulename: irq-bcm2835.ko

and/or

bcm2835_timer.ko

and/or

clk-bcm2835.ko

and/or

clk-bcm2835-aux.ko

and/or

irq-bcm2836.ko

and/or

bcm2835-pm.ko

and/or

board_bcm2835.ko

configname: CONFIG_ARCH_BCM2835

Linux Kernel Configuration
└─>Broadcom BCM2835 family
In linux kernel since version 3.1 (release Date: 2011-10-24)  
This enables support for the Broadcom BCM2835 SoC. This SoC is
use in the Raspberry Pi, and Roku 2 devices.

source code:
drivers/irqchip/irq-bcm2835.c

depends
 or CONFIG_ARCH_BCM |
| CONFIG_ARCH_MULTI_V6 or CONFIG_ARCH_MULTI_V7

is selected by
CONFIG_BRCMSTB_L2_IRQ