meta-arm-bsp: Enable conditional SVE configuration

This commit introduces conditional SVE (Scalable Vector Extension)
configuration. The condition
is based on the value of the 'SVE_DISABLE_FLAG' variable, which, when
set to '1', disables SVE features.

Changes made in this commit:
- In 'conf/machine/fvp-rd-kronos.conf', the 'TUNE_CCARGS_MARCH_OPTS'
  variable is updated to include '+nosve' when 'SVE_DISABLE_FLAG' is set.
- In 'recipes-bsp/trusted-firmware-a/trusted-firmware-a-fvp-rd-kronos.inc',
  the 'EXTRA_OEMAKE' variable is updated to include architecture and SVE
  parameters only when 'SVE_DISABLE_FLAG' is not set to '1'.
- In 'kas/fvp-rd-kronos.yml' Introduced 'SVE_DISABLE_FLAG'

Signed-off-by: Divin Raj <divin.raj@arm.com>