arm64: tegra_defconfig: fix duplicated symbol assignment.

arm64: tegra_defconfig: fix duplicated symbol assignment.

Below warning is seen during kernel build:

arch/arm64/configs//tegra_defconfig:8:warning: override: reassigning to symbol IRQ_TIME_ACCOUNTING

It seems to be bad conflict resolution during cherry-picking changes.
This patch removes duplicated IRQ_TIME_ACCOUNTING assignment.

Bug 2049432

Change-Id: Ieca6f6c0e1f21a530f02168f9f76fdfaf92d7bb0
Signed-off-by: Leon Yu <leoyu@nvidia.com>
Reviewed-on: https://git-master.nvidia.com/r/1945439
GVS: Gerrit_Virtual_Submit
Reviewed-by: Bibek Basu <bbasu@nvidia.com>
Reviewed-by: mobile promotions <svcmobile_promotions@nvidia.com>
Tested-by: mobile promotions <svcmobile_promotions@nvidia.com>