[FS#124] OpenSSL assembler optimisations for ARM

[LEDE Bugs]

The following task has a new comment added:

FS#124 - OpenSSL assembler optimisations for ARM
User who did this - dissent1 (dissent1)

----------
Can we enabled it for specific boards then?

ifeq ($(BOARD),ipq806x)
OPENSSL_TARGET:=linux-armv4-openwrt

for example?

Or add extra string into target config like CONFIG_arm_asm_opt=y with related condition into openssl Makefile? 
----------

More information can be found at the following URL:
https://bugs.lede-project.org/index.php?do=details&task_id=124#comment334